I've heard the Star Wars rumor as well, but beyond that I don't know anything. This summer is gonna be fun for me..I'll see most of the movies mentioned and then I'll see the Bourne Supremacy (sp?) and I think Aliens vs. Predator 2 comes out in August as well.
As for Terebithia...I'll be passing on it. I wasn't fond of Narnia and Terebithia doesn't even remotely interest me. Narnia and Terebithia are way too close (style wise and scope wise) to Lord of the Rings. They are shot the same way as well, that was actually the first thing I noticed about the Narnia trailer...it felt too much like a LOTR rehash. I did eventually see it at a discount theatre and wasn't that impressed. It was kinda interesting, but the parts I enjoyed the most involved the beavers.
I say bring on "Star Wars 3D"....what else does a summer need? Oh, that's right....I forgot about "Empire Strikes Back 3D". Nothing else matters. I do know that they are working on turning all the Star Wars's into 3D, just not sure when they were planning on releasing them. This summer would be nice though....