I've had my 32gb 3GS for 2 weeks now and the battery life was weaker than my 3G. It wasn't too noticeable but I could tell it wasn't showing better performance or performance equal to that of my 3G. I took it to the Apple Store today and a Genius told me that they have diagnosed the problem from backups from previous iPhone models. She said that the power settings for the 2G iPhone and 3G iPhone were designed for the type of hardware that the phone ran on. Now that the 3GS has a stronger processor and graphics card, the power settings are different. I was told to restore my iPhone as a New Phone. I did this and so far the battery seems to be stronger. I've only had it running for today so far but I notice that the battery meter is much more accurate and the battery % isn't ticking down as quickly as before. Now I don't know how much truth to this Genius' story there is, but I'll take it for now. At least until 3.1 comes out.