Yesterday I unplugged the phone at 7:30am and got the 15% warning at 1:00am. I was downloading updates from the Market and it was down to about 10% by 1:30am when I went to bed. I've only had the phone a week but what seems to kill the battery for me is the screen time. The standby time is good.
Are you guys doing lots of network network checks like constantly updating Twitter, Facebook, stock ticker, etc.? I have a synced Google account but I keep my other stuff set to check once every few hours or have automatic updates disabled entirely. I just manually refresh the content when I open the app or when I want it (with Facebook, Plume, and Pulse it is a simple "pull down and release" action to refresh). With "instant" Gmail and texts I find I don't need anything else polling since I can always get notifications I need via email or text. YMMV but I'm not having an issue making it through a 16 hour day.