The notion of Tobi being the leader was ever slightly acknowledged in the latest chapter, and many people have taken it to heart that he is. As of now, Pein is still the leader behind Akatsuki as no formal confirmation of Tobi's role or identity has been stated.
Along those lines, I have to agree with Chuchino. As I already said a couple of pages back, I don't believe Tobi is Madara at all, and I'll strongly oppose anyone who thinks so. Of course, I may be wrong when he is revealed, but I truly believe he is of another lineage in the Uchiha clan. The Obito theory is still up in the air and I support it much more highly than the theory of Tobi being Madara. And again, like Chuchino said, Madara was more of a historical figure, and I doubt he would want world domination on his to-do list, especially since he'd be 90+ years old if he were still alive.
So, as of now, Pein is still the official leader of Akatsuki, and Tobi is still Tobi, except now we know he has another personality other than the one he adopted with Deidara. He may also be Obito, and he could be Madara, but no one knows.
Let's continue the speculation!