I'm with Meteor. I updated to latest firmware via kies the other day, but that hasn't affected the battery life, it was fine before, and it's fine now.
I don't know what to suggest. On my S1 I was charging every half day (at lunch time) and if I didn't charge then I didn't have the phone for the evening, basically.
The S3 conquered this problem for me. Can't wait until they can make a battery that lasts a week/month/year etc. lol