I haven't run a task killer in several months after reading multiple posts in the forum, and my battery life improved on 2.1 as a result. Not stellar, but better than with a task killer. But my battery life has decreased back down to what it was when I ran a task killer since updating to 2.2. I unplugged with a fully charged battery at 7:55 a.m. and I'm now at 60% just 4 hours later with very light use (since I'm at work). I've un-synced all the additional stuff 2.2 was automatically set up to sync. I'm hoping it levels out after a few cycles.
The thing about smart people is that they seem like crazy people to dumb people.