XM Satellite Radio and Napster announced on Wednesday a long-term partnership to develop a music store where listeners with XM-equipped MP3 players could mark songs for download at a later time. The store will be called "XM + Napster" and will be the exclusive store for XM music downloads.

Since the deal is exclusive, it kills any speculation that Apple may release an XM-capable iPod. Apple's music device is incompatible with the digital rights management technology that Napster uses, called Janus.

This announcement comes one day after XM announced a strategic partnership with Samsung to develop two MP3 players with XM's Connect-and-Play technology. The Samsung players would allow a user to mark certain songs they hear on an XM channel to be downloaded from the music store at a later time.

Other players due later this year would utilize the same concept.

Once connected to the PC, the player would find the marked songs on the Napster service and download them to the user's computer and the device. The service would also allow listeners of XM Radio Online to perform the same function by purchasing music they hear.

"The combination of the 'XM + Napster' service with new XM/MP3 players will provide XM subscribers with the ultimate 360-degree music experience," said Hugh Panero, XM president and CEO.

"Today, XM subscribers can effortlessly discover and listen to any kind of music, and soon they will be able to effortlessly access, purchase, and manage their music with 'XM + Napster' and the new XM/MP3 players."

XM expects the service to be launched in the fourth quarter of this year in conjunction with the release of compatible players.