Well, in IMAX, anyway.
Apparently, the IMAX release has some extra footage. Revenge of the Fallen had some extra footage in the IMAX release as well, but it was only a few minutes.
Dark of the Moon is supposed to run about 134 minutes, so in IMAX that's about 20 minutes of extra footage.
I hope it's all added to the Chicago battle. It's supposed to be huge; I'm pretty excited about it.