Michael Bay has been posting some brief updates on Tranformers 3 on his official “Shoot for the Edit” site lately and he’s dropped a handful of hints:

Busy scouting - Chicago, Detroit, and Washington D.C. for Transformers last week. Things are going well. The script is feeling very different from the other two.

And, in quoting an L.A. Times article:

“There will be a nice crescendo ending,” Bay said. “It gets much more into the robot character. The last time you kind of met a few of the robots; this time you’re gonna get a much cooler landscape.”

Considering how disappointing Transformers: Revenge of the Fallen was, it’s nice to hear that the script is feeling “very different.”  Maybe this time they’re actually bothering to fashion a coherent film before filming begins.