it is possible that itachi is the akatsuki's leader. hahaha.

ok anyway. but seriously, i don't think the akatsuki has an actual leader. i think they are sort of like the evil justice league. they're just all super powerful bad guys who got together to do what needs to be done. there are no leaders but they are able to work together and agree on capturing all things related to jutsus. also, i think itachi is one of strongest in the group, if not, the strongest or the one the nins should be most cautious and concerned about. i don't think we'll see someone who is even more stronger than itachi. but if that happens, it'll be WAY later on in the story, as orochimaru and itachi are almost god-like right now.