From MP3tunes

PalmOS does not come with a media player that supports streaming M3U playlists. Consequently, the Mobile Site does not work on these devices out of the box. Fortunately, third party music software is available for PalmOS devices that does support this functionality. After installing one of these third party players the Mobile Site should work on your device.

Applications Known to Work

Kinoma Player

* Available at: http://www.kinoma.com for $24.99
* Supports streaming from the mobile site

Pocket Tunes Deluxe

Note that the version of Pocket Tunes included on newer Treo models is the Basic version which does NOT support streaming.

* Available at: http://www.pocket-tunes.com for $37.95 (Free trial available)
* Supports streaming from the mobile site
* Supports background operation