I started at 90%, went out to the pool (full signal the whole time), listened to music and used safari / tweetie for maybe 10 minutes combined - and I noticed the % go down every other minute!! Is this normal? I listened to music for maybe 1-2 hours total, and my battery life is now 14%.
I've found battery life to be vary variable depending on what sort of reception you have. The better the reception the better the battery life..
(and ofcourse taking into account all the usualy location services, bluetooth, 3G etc suggestions.)