If you think your iPhone 4S battery might be draining too quickly, there are a few things you can try to plug the leak.
Go to Settings > Location Services > System Services (scroll all the way to the bottom) and try disabling some of those options. Edmund told me he saw some great results after turning off just the Time Zone service, but your mileage may vary.
Many iPhone 4S owners claim to not notice any battery problems, so the actual cause seems to be elusive. Most likely it’s a bug or two that Apple can squash in what I assume will be a 5.0.1 update.