The US Al Qaida one has all the marks of a fake. Whether it's a semi-offical fake, a semi-unofficial fake, or an entirely private effort, that's open to speculation.

The Bin Laden one seems genuine, though I'm sure there'll be conspiracy theories about it. On balance, I'd have thought it should help Bush, and I'd say that's probably one aspect of the thinking behind it, and the timing. But it could work the other way. I'd have thought the main idea would be to ensure a massive audience, and massive media coverage at the heart of the election as the world's eyes are focused on it - this is show business.

Either way he wins. If it pushes people towards putting Bush in, he's got the best recruiting sergeant in the world for Al Qaida back in the White House. If Kerry gets in, that will be spun by a whole lot of people as being because of this tape, which increases Bin Laden's street cred round the world.