This new battery (PSP-280, 2200mAh) is the same size/dimensions as your current rechargeable PSP battery, but will up your current capacity by 20%. Price: 5,300 Yen, about $46.00 US (may be $50 by the time it reaches the states?).

Also, a new 1GB PSP Memory Stick Duo (PSP-MP1G) - pretty the same as regular 1GB Memory Stick Duos, but with the PSP logo on it! 

All news credit go to this wonderful article/site:
http://psp.ign.com/articles/655/655563p1.html

*Concura