Look, I'm going to go out on a limb here and accuse Activision of being sneaky. I think the information that is being 'leaked' early is their way of catching up on marketing a game that should've been marketed months ago given its early November release date. The information was supposedly leaked due to the changing of the guards - in this case developers - now that the game is complete enough to start the final coat of polish. Other developers step in and apply that coat. Some of those developers appear to have sticky fingers. Bah, rubbish.
This morning the first thing I did was check for a live stream of game 4 of the NBA Western Conference Finals because that's where Activision were to premiere the launch trailer. They had previously 'rushed out' three teaser trailers detailing the four big locations in which Modern Warfare 3 will take place, but this would mark the first real footage of the game. At the time of writing this article, Game 4 hasn't started yet. I have watched the trailer. Joystiq.com just ran it. The video they showed has since been pulled but for every video that's removed, three spring up in its place. Again, I don't think it was leaked. I think it was released early.
It's the same principle as pricing yourself according to the prestige that you want to set. Audi A3 is 30% more expensive than a VW Golf. They're the same car made in the same factories. Audi charge more and people know it's better. Leaking information implies that it's so hot that people are literally stealing it.
But let's face it, it freakin' is.
The trailer doesn't show much more than what you could have already imagined after watching the four teaser trailers, but at least it's something. It looks polished, it looks better than Black Ops. I can't stop shaking like a puppy that needs to go outside. Here it is, hopefully it hasn't been 'pulled down'.