I took my first iPhone 3G (week 30 build) into the genius for light leak and dust under the screen. The new one is a week 34 build and I swear the battery lasts longer on this new phone. I switched off 3G just like I did on my last phone to help conserve power. Before needing charging my phone got to 5 hours and 8 minutes of usage and 3 days, 9 hours of standby. I've never had these times with my first phone.