That's pretty much what I was thinking as well, though sort of the other way around.
The anniversary itself isn't until November, and I think the anniversary episode marks the beginning
of the real anniversary celebration, rather than it's climax. I don't think we'll build up to it, per se, but that the Nov 23rd ep will mark the start off a year long anniversary story arc/celebration, that'll include the Christmas special and virtually all of series 8, and reach it's climactic conclusion nearly a year later on the fields of Trenzalore.
I'm expecting a whole anniversary series that starts
on Nov 23, 2013, rather than a regular series that ends
on that date with a standard 60 minute episode wherein the only thing about it that qualifies it as a "special" is that it's being shot in 3D.