As for madara isn’t there something kind of wierd in the fact that we have not seen his face. or at least all of it.
And if he is immortal as he claims he is why does he only have one eye.

Concering Madara=Danzou:
1.Kisame (Madara´s student!) comes from the same village, where Sai was to get his feeling erased – by Danzou´s order. you can read it in the chapter when he gets his picture book back in oro´s base (dunno the number)

2.Anybody thought about OBITO = DANZOU?
I mean the eye, the blessures and so on

Coming conflict Pein-Madara:
Pein wants worldwide peace, but Madara?
In a former chapter, Pein explains to gain world government, but I think this was only to get pawns (world dictatorship and peace don´t fit, after ultimate jutsu, there´d be no world to reign and both of his explainations bout akatsuki´s aim in front of akats and infront of Jiraiya are contradictory anyway)
I can´t imagine Madara to struggle for peace, when considering his fight against the foundation of Konoha (like he said himself).
So there´ll may be another turn-around in the story – Akatsuki, too self confident right before reaching their “common” goal, gets torn apart by traitorship and inner conflicts (Pein-Madara)

Most likely all of these things have been said before, but i´m too
lazy to read all comments, so sorry for repetitions ^^

1. He uses a technique similar to a mixture of Kage Bunshin and Orochimaru´s necromancy jutsu, but perfected by Rinnegan. That´d mean he´s still alive and pulls strings from the background.
This would match to the image developed in his fight against Jiraiya sensei: Always keeping something back, hiding in summoned animals, having a backup-force in secret …
This seems very likely because lots of akatsuki-members (Oro, Kakuzu, Madara?, Sasori) use dead enemies.
Furthermore, around ch 256, he transfers Itachi´s and Kisame´s consciousness into other persons, which he could do himself, too.

2. He has become a god-like existence and has somehow melted with the others to one confidence (seeing the same) that also comprises the other individuals (Nagato and so on). Philosophically said “transcendental” (I dunno if it´s the right translation – I don´t trust the online translator – I mean the expression formed by Kant)

You have to consider that Pein never called himself Nagato, Yahiko and so on, so he obviously doesn´t regard himself as one person but either as a result of pain (then he could still be a single person) or like in 2.

Concerning using-dead-body techniques:
It´d be interesting if Kishimoto lets Naruto fight against Pein in the form of Jiraiya and his mother.