Ever since upgrading my iPhone 4 to OS5, my battery doesn't seem to last as long as it used to. When I find suggestions for extending battery life, I try it, but it doesn't seem to help. I found another solution, and for some reason, this seems to have helped more so than any other suggestions.
As most iPhone users know, when you double click the home button, it brings up the most recently used apps. If you hold your finger on one of those apps to make it wiggle, they will do that "jig" that they typically do. The difference is there is a minus sign instead of an x. If you click on the minus sign and close each of these apps out, it helps to extend your battery life. MAKE SURE IT'S A MINUS AND NOT AN X, or you're going to delete your app completely from your phone rather than just from your recently used apps.