No, the IMAX CG shots were done in 8K, which is the full resolution that normal 35mm film scans at. That's why it was passable - normally, 35mm CG shots are done at 2K. All CG is done at lower resolution than a full film scan.
Well, a big part of it is that it's TRANSFORMERS. We all know action scenes involving big giant fast-moving robots cannot be done for real.
Bay can blow up a lot of things real pretty, and if he was going to shoot that in IMAX, I'm sure it would look fantastic. I just think the current situation is misleading, since he makes it sound like the Transformers robots will be nothing but shot-on-IMAX-film-awesomeness, which is simply impossible at this point in time.
I have no idea what their logistical approach of the CG rendering is right now, anyway. None of the press releases state it. If by next year, it's publicized that Bay and his team developed 18K CG robot shots, then that's great and I will take back everything I've said. But as of now, I can very safely assume that isn't going to happen.