I don't think it's him. Osama Bin Laden, I mean. Bin Laden is actually a fairly handsome man, based on validated photos; this guy is ugly. He seems to have changed his turban. The face doesn't narrow as much toward the chin as in earlier photos, the nose seems broader at the base, and why would he suddenly trim the beard? Isn't he Mr. Islamic Fundamentalist, who never trims his beard? Not to mention, why would he suddenly dye his beard? The beard in that photo is dead black, and earlier Osama photos have shown everything from streaks of white to full gray. I think they have a younger body double for the photos, operating on the theory that one Arab man with a full beard looks much like another, and the quality of the videos is crappy. I'm not sure about the voice; but they could have a voice double too. Chris Regan, on Fanatical Apathy the other day, linked to a video he did in which he imitated FDR, and it was brilliant; I've heard FDR recorded, and I couldn't tell the difference. If Chris Regan can do FDR that well, Al Quaeda could train a mimic to talk like Osama.
Personally, I think Osama Bin Laden has been dead for at least a couple of years. Remember, this man's kidneys were bad: he was on dialysis. And he couldn't just drop into the local hospital for treatments: he had to carry the dialysis machine, and power for same, around with him from hideout to hideout. He has/had the money to do all this, no doubt; but it seems like a situation where it wouldn't take too many things going wrong all at once to be fatal over a relatively short period. I don't think he made it out of Tora Bora. But his mystique is so strong there's a powerful incentive for the remaining inner circle of Al Quaeda to keep releasing videos of him (with the background carefully blurred), to convince the world that he's still there and still a threat. Nobody else has that kind of mana.
The final reason I don't think it's him? This absurd suggestion that Americans should convert to Islam if we want to end the war in Iraq. That's just stupid, and while I dislike Bin Laden, he's not (or was not, if I'm right) stupid, and I don't think he would waste valuable broadcast time on a suggestion that is about as rational as the Pope suggesting that all Muslims should convert to Catholicism. That statement came from a not very bright ideologue, whose religious impulses overrode his brain; and nobody ever said that about Bin Laden.
Furthermore, if we all did convert to Islam, it wouldn't do a thing about the war in Iraq; and Osama Bin Laden knows that (assuming he's still alive). That's a local civil war among internal groups, most of whom hate Osama Bin Ladin and Saudi Wahhabism as much as they hate Americans. Shias versus Sunnis; Shias versus Shias (check out Basra and environs); everybody versus the Kurds; and the vast majority of the combatants are Iraqis. No matter what the neocons say about "Al Quaeda in Iraq". Sure, there probably are some foreign jihadis running around hoping to achieve martyrdom while taking a whack at the Great Satan; but they're a minority. How many times do we have to say "civil war"??