Basically, it comes down to this: Summer 2011 is going to be one of the most competitive summers ever. X-Men FC, POTC 4, Thor, Captain America, etc... there's no shortage of blockbuster movies coming out. But it's a pretty safe bet that the two heavyweights are going to be Transformers 3 and the final Harry Potter (I can't see how any movie is going to top the final HP movie box office wise). And that's my point: from what I can tell, there's only been 1 sneak peak of the HP movie. No trailers, no Super Bowl commercial, nothing. Biggest movie of the summer, and so far, zilch. So it makes sense that TF3 has held back. The smart move is to counter the HP promotion with their own, so the big bad trailer we're all waiting for is probably going to go live right before or at the same time the HP trailer comes out. It's a competition, and while neither movie is really gonna need much marketing, it's going to be an all out battle anyway. That's my theory, anyway.