Meant to post this like two weeks ago, but as is usually my wont I forgot all about it. My bad. . .
Like many, since the first links to these covers were from Amazon.com, I thought that these were the new North American covers. But after checking with the folks at Daw Books, I learned that this wasn't the case. They do plan to repackage the trilogy, but not now. And since then, Orbit confirmed that these were the new UK covers for the mass market paperback edition of Memory, Sorrow, and Thorn.
Though I found the Otherland series superior, the fact remains that Tad Williams' Memory, Sorrow, and Thorn is a "must read" series for all fantasy fans. Be sure to check it out, if you haven't already!
The new cover art looks great, but I will always have a soft spot for the originals!