Quote Originally Posted by iMUSTbeTHEdevil
So who ever he was talking to in the dark, looked to me like he was missing his left arm. So who in the series is missing an arm?....

-dg-
I think the person in the dark must be Danzo. If you look at the place where Pein is at, you can see it's very similair to the place where Danzo and Sai are talking. Danzo is also missing an arm and he has his reasons to take revenge on Konoha. I guess we'll see later on, but I'm pretty confident that I'm right about this.