A chess.com staff member said that they are not actively working on an app for WP in this thread: http://www.chess.com/groups/forumview/beta-code-for-online-chess-using-windows-phone-7
Message BitBlitz for an invite to this group: http://www.chess.com/groups/view/npchess-client-beta
Is it likely that chess.com will be developing an app for windows phones? I just got a Nokia lumia and its breakin' ma heart having to play chess by post.