The Shadow Tree has been finished but the only way for it to be released is to show the publisher the sales of the Dormia series are strong. So for that to happen buy Dormia and The World's End for your friends, family, cousins, or for anyone who you think might enjoy the book at Amazon or Barnes & Noble websites. If this doesn't happen The Shadow Tree will sadly not be released and all the wait will be worth nothing. So if don't want that to happen then what are you waiting for, go purchase the books.
Sources: The Dormia Tribune email update []