What is claimed is:1. A computer-implemented method, comprising:receiving, at a computing device from a first user device, a first streaming request to stream content to the first user device;transmitting, from the computing device to a service provider computer, the first streaming request to stream the content to the first user device, wherein transmitting the first streaming request to the service provider computer causes the service provider computer to stream the content to the first user device, the first user device playing the content subsequent to receipt;receiving, from the first user device, an index indicating a past position reached during playback at the first user device;maintaining, at the computing device, state information associated with a user profile associated with the first user device, the state information comprising the index received from the first user device;receiving, at the computing device, a subsequent streaming request;in response to the subsequent streaming request, identifying, by the computing device, subsequent content to be streamed to one or more user devices that are different from the first user device, wherein identifying that the subsequent content is to be streamed to the one or more user devices is based at least in part on the state information associated with the user profile;transmitting, by the computing device to the service provider computer, a second streaming request to stream the subsequent content to the one or more user devices, wherein transmitting the second streaming request to the service provider computer causes the service provider computer to stream the subsequent content to the one or more user devices, the subsequent content being played at the one or more user devices subsequent to receipt and from the past position reached dining the playback at the first user device; andupdating, by the computing device, the state information associated with the user profile based at least in part on the subsequent content being streamed to the one or more user devices.2. The computer-implemented method of claim 1, wherein the subsequent streaming request is received from a second user device, the second user device being different from the first user device.3. The computer-implemented method of claim 1, wherein the subsequent streaming request includes an indication of the one or more devices to which the subsequent content is to be streamed.4. The computer-implemented method of claim 1, wherein the content streamed at the first user device is the same content as the subsequent content streamed at the one or more devices.5. The computer-implemented method of claim 1, wherein the second streaming request comprises the index, and wherein the service provider computer begins streaming the subsequent content according to the index provided in the second streaming request.6. A computing device, comprising:one or more processors; andone or more memories configured with computer-executable instructions that, when executed by the one or more processors, cause the computing device to:maintain state information describing aspects of historical content streaming associated with a plurality of user devices corresponding to a user profile, the state information comprising respective indices received from respective user devices of the plurality of user devices, an index of the respective indices specifying a past position reached during playback of content at a first user device of the plurality of user devices;receive a streaming request for the content from a second user device of the plurality of user devices;select, based at least in part on the state information, the content to be streamed in response to the streaming request; andtransmit a request to a service provider computer, the request indicating the content to be streamed and the index specifying the past position reached during the playback of the content at the first user device, wherein transmitting the request to the service provider computer causes the content to be streamed to one or more user devices of the plurality of user devices beginning at the past position reached during playback of the content at the first user device.7. The computing device of claim 6, wherein executing the instructions further causes the computing device to select the one or more user devices from the plurality of user devices based at least in part on the request and the state information.8. The computing device of claim 6, wherein the state information corresponds to a last streaming of the content and further comprises a device identifier for the first user device of the plurality of user devices and a content identifier corresponding to the content streamed at the first user device of the plurality of user devices.9. The computing device of claim 6, wherein the second user device is one of the one or more user devices at which the content is streamed.10. The computing device of claim 6, wherein the one or more user devices comprise multiple user devices of the plurality of user devices, wherein each of the multiple user devices is associated with a group identifier, and wherein the request comprises an indication of the group identifier.11. The computing device of claim 6, wherein the state information comprises a volume level at which the content was previously presented, wherein the request indicates the volume level at which the content was previously presented, and wherein the content is streamed to the one or more user devices at a volume corresponding to the volume level.12. The computing device of claim 6, wherein the user profile is associated with a subscription identifier, and wherein executing the instructions further causes the computing device to determine that streaming the content to the one or more user devices is allowed based at least in part on the subscription identifier associated with the user profile.13. The computing device of claim 6, wherein the state information comprises one or more device-specific attributes, wherein the request comprises the one or more device-specific attributes, and wherein a particular version of the content is selected for streaming to the one or more devices based at least in part on the one or more device-specific attributes.14. A computer-readable storage medium comprising computer-readable instructions that, when executed by one or more processors of a computing device, cause the computing device to perform operations comprising:receiving, from a first user device, a streaming request for content that was previously played, at least in part, at a second user device;obtaining state information comprising an index at which playback of the content at the second user device was halted; andtransmitting, to a service provider computer, a subsequent streaming request comprising at least the index and indicating the content is to be played at the first user device, wherein transmitting the subsequent streaming request to the service provider computer causes the service provider computer to stream the content to the first user device for subsequent playback, being streamed to commence the subsequent playback at the first user device at the index at which the playback of the content was halted at the second user device.15. The computer-readable storage medium of claim 14, wherein the subsequent streaming request comprises an identifier associated with the first user device and a third user device, wherein executing the instructions further causes the computing device to perform further operations comprising identifying the first user device and the third user device based at least in part on the identifier included in the streaming request.16. The computer-readable storage medium of claim 15, wherein the subsequent streaming request comprises identifiers for the first user device and the third user device, and wherein transmitting the subsequent streaming request further causes the service provider computer to commence playback of the content at the third user device in addition to the first user device.17. The computer-readable storage medium of claim 14, wherein the state information comprises one or more filter attributes, and wherein the service provider computer selects a particular version of the content to play at the first user device based at least in part on the one or more filter attributes.18. The computer-readable storage medium of claim 14, wherein the state information comprises one or more device attributes, and wherein the service provider computer selects a particular version of the content to play at the first user device based at least in part on the one or more device attributes.19. The computer-readable storage medium of claim 14, wherein executing the instructions further causes the computing device to perform further operations comprising:identifying, from the state information, that a first instance of content and a second instance of content are individually being played at two corresponding user devices; andtransmitting, to the second user device, a request to identify the content as being the first instance of content or the second instance of content.20. The computer-readable storage medium of claim 14, wherein the service provider computer operates as part of a music service.