Tobi finally unmasked.
[HIDE]And yep, he's Obito Uchiha.
Though now in order for Naruto's birth to work, the modern Tobi couldn't have been the only one to have been the Masked Man. Since I don't think he would have been old enough to have fought Minato back then.
I'm thinking that the past Tobi really was Madara. Perhaps after those events he passed on his mission to the current Tobi then died. Madara being the one that saved Obito in the first place. This would explain how Tobi & Madara knew each other and why the current Tobi claimed to be Madara until Kabuto revived the real one.[/HIDE]