UPDATE: It's fixed. Go here for details.
UPDATE: If you need to load in a framed state, disabling the Spockholm toolbar works. Team Spockholm has been notified.
Mafia Wars players are used to the white screen load but this time it's affecting all games. Thankfully there is a work around as loading the game unframed will work. Since this is affecting all Facebook games, I imagine it will probably be fixed sooner than later. The Facebook known issue page can be found here.