Same issue here. My phone went dead at 5pm yesterday. It was fully charged when I unplugged it at 7:30am and I barely used it. "Voice calls" and "Android System" were the biggest battery uses which is really bizarre. Today I am already at 80% after 2 1/2 hrs of almost no use.
Check this out... if you go to settings > Accounts & sync
Watch the bottom of the screen and the gmail account sync. Something keeps flashing every 7-8 seconds at the bottom of the screen but its so quick I almost can't read it. I think it says "Sync is currently experiencing problems. It will be back shortly." The gmail sync flashes red for a split second at the same time. I think this is the culprit.
I turned off sync and pulled the battery. When turned back on and went to the sync screen the error message stayed on screen and
______@gmail.com showed "sync error" and a red symbol. I reactivated all the syncs and the sync symbol and flashing problem came back.