I have both SBSettings and Activator too (among a bunch of other jb apps) and I'd noticed that my battery life after the jb (3GS) had gotten pretty bad.
A few days ago I decided to run the battery completely out and then recharge it to 100% to see if it would make any difference. It did. I've gotten fantastic battery life since doing that, so maybe try it?
The numbers, just off the top of my head...before draining the battery, I would use the phone throughout the day to check things like Twitter, Facebook. I'd use Safari to check in on my fantasy football...in other words, things that drain the battery. By the end of the night, I'd have 10-20% battery left.
After draining it and doing the exact same things, I've now got about 40-50% battery life left at the end of the night.