http://psp.ign.com/articles/574/574557p1.html
I was actually shocked when I read this... I seriously thought Sony would have done better. xD
Basics of what the articall says:
Ridge Racers running at around 60fps, with advanced visual effects, full brightness on the screen, and full sound, no WiFi and low disc access; the battery lasted a whopping 3 hours, 32 minutes.
Then, on low intensity games, like Mah-Jong. With the screen and volume on full (volume using headphones this time), freaquent disc access, and again no WiFi; the battery lasted 5 hours, 9 minutes. So it would seem that a game that doesn't use great amount of intense processes, lasts a little longer.
With the system in complete sleep mode, the battery life on a full charge, it lasted more than 24 hours... But so can the DS (if not longer)
Running Ridge Racers in WiFi mode with full brightness and volume will earn you an action packed 2 hours, 46 minutes of play.
And they also test the MP3 battery life of the PSP (with screen off and volume high, and constant memory stick access) and came out with 10 hours, 39 minutes... thats good for playing MP3s... but who is gonna use their PSP to just play MP3s...
Well, thats pretty much what the artical says.
Even with the most basic games it doesn't do much better than 5 or 6 hours... pfft...
*hugs Nintendo DS* I'll be much happier with my cheaper DS and its 12 hours of battery life.