I think the person in question is the bearded guy, who Niobe meets in the subway in Enter the Matrix. The old tramp who says “72 hours… That’s how long Zion lasted the last time.” And then he vanished into the darkness, chuckling ominously.
There’s a glimpse of him in the Revolutions trailer. Someone just decided to call him the Timekeeper, for Neo knows what reason. He calls himself an Observer. So we should name him THE Observer.