[From Hans]
Coming through Engadget with sources at Palminfocenter and TreoCentral, "the phone will use the exact same battery as the Treo 800w and the Centro -- a 1150mAh model. Apparently Palm reps were happy to snap the back off the device and show the source of its juice off. That same size battery is used in the G1 as well" Jump for more deets.