I have a Nexus One, and since upgrading to 2.3.3, my phone lasts several hours less compared to 2.2.x. I've swapped out to a new battery, which didn't make a difference. In about 14 hours (of nothing more than texting), my phone is at less than 15%. When I check the Battery use under Settings, Android OS is always the top battery consumer.
What can I do about this? Every other update besides this one has been great, but Gingerbread is a total disappointment.
Update: This is 100% an issue with wifi. After disabling it, the battery usage of Android OS has dropped from 40% to 2%. After 16 hours on battery, it's still more than half charged. I'll keep investigating...or revert, because I think Gingerbread just looks fugly.