We've just gotten the 2.3 update (2.42 to be precise) and i am amazed at how much better the battery is
I had the wifi, bluetooth, GPS (had a sat nav & GPS tracker running) 3g on, music playing & left the screen on for about an hour & had obly lost 14% of the battery, i bet pre 2.3 it would have been half dead....
Amazing how much battery those background apps take up & i'm grateful HTC had to chop a load out to fit them onto these phones

My only gripe though is the menu now looks disgusting :/ i dont like my apps tabbed into sheets, i like them all on one page