There are at least two posts in the official NWN2 forums by posters with NWN2 badges (meaning they've registered their CD keys, and hence have received their copies of the game) indicating that either the game has shipped with a beta version of the DM Client on it, or that it was available in a patch right away.  Which of the two wasn't clear in the posts, but the good news is obviously that there is a DM Client.  The posts from the official forums are here and here.  Discuss in our forums.