Well, here's what it says on his site:
COMING SOON: A new Trek background book from me! Best of all, it's gap-filling canon—non-fiction lives! Stay tuned for details about a new maps/book set, officially licensed by CBS. Out this fall. ...
More maps! Yay! I love that sort of stuff, and am very happy to see that we're getting stuff new material.
Will be interesting to see what kind of questions answered/questions posed ratio this one has.