I just googled myself (c'mon, admit it, you do it too) and found out that the three books coming out in January are available to preorder from both Amazon and Barnes & Noble. And I'm certain that you could preorder with your favorite local bookseller as well (or if not, then soon).
It looks like they're also going to be available in paperback!
So, go ahead, preorder! I've seen the layout and they're awesome--I can't wait for everyone to see them! And of course, I'll sign them if you buy them!
WHO REALLY DISCOVERED AMERICA
This link will take you to the books page of my website (page down to the bottom)--I linked the books to Amazon for convenience, but please do remember your local independent bookseller when you purchase. Mine is Willow Books and is located here.
Update: the cover images are visible on my profile page on GoodReads. Whoot!