"all of Intel's Centrino partners have indicated they will announce notebooks based on the new Montevina Centrino 2 platform at that time"
But other companies "announce" in advance of shipping. So don't expect shipping computers in June, just announcements. And since Apple doesn't pre-announce products, you won't hear anything from them until July or August, when they are ready to ship.
As for the case redesign, if that potentially includes the new keyboard I'll think I'll be picking up one of the just announced models. I've used the new keyboard a little bit; and while I'd probably get used to it, maybe even like it, I'm not willing to bet $2500 on it.
I think it is great that the redesign will come with Montevina. I own a Macbook Pro of last revision and was till yesterday every eager to know if the lastest update has a new design. As it's only a spec bump I am very relieved that I don't have to sell my current notebook and buy a new one. So I will until July and buy the redesigned and MUCH faster Montevina Macbook Pro. Hopefully Apple will announce a redesign of Macbook Air with more space and ports.