found something
Okay some headway made.
HDCrazy on the mac forums discovered that if you're on iOS 4.3.5 or 4.3.3 that there's a problem with the exchange email and iCloud that causes weird battery calibration and overclocks your chip (hence the hot phone even when idling). A several people have reported partial success with this including myself.
1) Remove all your email accounts. Especially your mobileme/icloud email.
2) Deactivate everything in iCloud settings. When prompted, keep all the info on your iPhone.
3) Hard reboot your phone. Press the power button (on top) and your main button just above the USB plugin on the main face. Hold these buttons until you see the white apple logo show up again.
4) Once restarted, go back and re-enable iCloud and restore all your email accounts.
https://discussions.apple.com/thread/3378076?start=0&tstart=0
Let me know how it works out for you.
I'm still not thrilled about the new battery usage but I did find a solution that doubled my battery life time. As I said above, I was going from 100% to 0% in 4 hours. Last night after doing this I was at 80% and went to 10% after 9 hours. In iOS 4.3.5 I would only drop about 12% in 9 hours...