taken from gameinformer interview with President And CEO Of SCEA Kaz Hirai
about the PSP:
Again, if you're just listening to music with no visuals at all then it should last, as I said yesterday, about eight to ten hours just like an iPod would. If you are playing a game that is consistently cycling through and putting the CPU to good use, yeah, battery life is going to be shorter. Maybe about two and a half, three hours.

2 1/2 hours battery life when you play a game?
Ooooooooookay
x_x

source:
http://gameinformer.com/News/Story/2...1354.39666.htm