I have heard that some people have some problem with calendar widget using lots of battery. And some IM widgets also use much. I myself have phone set to dual mode (stays on 3G at all times here), have bunch of widgets (calendar, media player, foreca weather and location) etc... GPS and GSM network location are enabled, but nothing should use those other than when I manually activate location widget or use some other program using location info. I do not have any IM widgets or anything that checks stuff from the net periodically. Foreca weather widget is set to update manually only (whenever data connection starts or I manually refresh it). I don't have much stuff on calendar though. Anyway, other than the Wi-Fi bug, I do not experience any problems with battery life.