I've heard a bit of speculation that Paul McGann might actually make an appearance in the new series, since there is apparently a new pic of him as The Doctor in a completely different outfit than before--this combined with the reappearance of the previous TARDIS interior is enough to lead some to this conclusion.
I don't know whether I believe that, but it would be really freakin' cool if it were true. Maybe it would be something about him at the end of the war?