I’ve heard rumbings of this for a few weeks now, but this seems concrete:
I work at a movie theater and we have the trailer on one of our X-Men 3 prints. I saw it last night (Wednesday). It’s alright - mostly text with a few clips of the movie in the middle. Total runtime is 56 sec. I should note that this will not appear on EVERY X-Men 3 print (from what i can tell). For example, our theater got 4 prints of X-Men 3 and the SoaP trailer only appears on one of them.
So, if anybody is desperate to see the trailer, call your local theater and find out which X3 screens the trailer will be running on. Please let me know when it shows up online, I’ll post the link.

Well, I’m sure that if I don’t see it before X-Men 3, It’ll be on the internet soon enough.