Napster and Motorola have teamed up on a co-marketing effort that in part will allow users to transfer, store, and play subscription music from Napster on their Motorola phones.

To do so, Motorola is adding Windows Media DRM technology to select music-enabled handsets, which will allow anyone with a portable music subscription to load their music on the phone like any other PlaysForSure device. Motorola unveiled two such phones today -- the ROKR Z6 and the Z6m.

Additionally, Napster will provide one month of free service to anyone buying a Motorola phone in the U.S. and Europe. European customers also get five free permanent downloads.

The two later this year will develop in-store "music experiences" at retail locations designed to promote mobile music services.