500 new features coming in the next update of Windows Phone according to Steve Ballmer

[From Eric Mann] 500 new features coming in the next update of Windows Phone according to Steve Ballmer. "Just how big of an upgrade will the Mango release of Windows Phone be? Try "500 new features" big. Steve Ballmer revealed that seductively round number in a speech over in Japan today, where he also said that additional information about "who's going to be building Windows Phones" will be forthcoming at tomorrow's preview event as well." Engadget after the jump.