Having come from a Palm Pre to now the Nexus S 4G, this is my first experience with Auto Brightness for the display. I wasn't really sure if it was beneficial or not (in terms of the battery), so I did some research and came across an interesting article (documenting research) on how auto brightness is joke (currently). Thought I'd share the article with my fellow new Nexus S 4G owners:
Why iPhone 4 and Android Brightness Controls Are Effectively Useless
Why iPhone 4 and Android Brightness Controls Are Effectively Useless