[spoilery] I have this theory that this fellow is not Leoben but a pivotal character, perhaps the Xeno Fenner fella who shows up in the final episodes and/or is the mad-scientist-who-explains-it-all-to-you character since it sounds like most of the big questions the creators and writers have left dangling will be wrapped up in a single episode (other blogs and scifi websites have posited that it will be the Islanded In A Stream of Stars ep). Several visitors to this blog say that clearly it is Leoben, but if you look closely at the man's face it is broader, and he has golden-brown eyes (like the actor hired to play Xeno) not blue as Leoben actor Callum Keith Rennie does. This man is clearly standing in the Cylon base ship C&C and wearing the same color shirt as a Leoben, but I think this is misdirection - SciFi has finally learned how to tease future eps by juxtaposing images, dialog and sounds without being so literal and giving away the store to anyone with even rudimentary deductive ability. The still image of this man was pulled from one of the 4.5 short teasers. It is possible it is Leoben, shot with what is called "monster lighting" but I don't think so.
I'm not always right. I'm just a fan who created this blog for fellow fans for the fun of it. I was convinced that Roslin would be the 5th and Final Cylon. Really, she should have been - it would have given the story more heft then some smaller story about a couple (Tigh and Ellen) that wanted to stay together through time.
I keep hoping for a return to the lofty heights of the miniseries and first season-and-a-half - with its grand ideas, mysticism and high-style, but it seems I am hoping in vain. Moore and the writers, according to repeated statements by actor Eddie Olmos, are taking us on a very bleak and ironic journey to a bitter end - down the dark mineshaft of cynicism.