Only phone that can play that is the Nokia N900 since it has firefox browser but I heard the Bolt Browser for blackberry can play Mafia Wars so you can give it a shot.
No! Flash Player cant do that... Flash Player on the BlackBerry® is only used for media or viewing media or playing media from the browser. if flash player would let you do all those functions on that handheld, your handheld could crash this is why the mobile flash player is not for games like that.