Back in July, IGN reported that the addresswww.modernwarfare3.com redirected
people towww.battlefield.com/battlefield3, EA's official site for its upcoming shooter.
Activision didn't get the joke, and took those who registered the address to court, where it had to provide evidence that the address was "confusingly similar" to its own trademark, that the previous owner had a lack of genuine interest in the usage of the address, and that they had used it in "bad faith".
If you want to peruse the specifics of the case, you can read the specifics of the decision.
Call of Duty: Modern Warfare 3 is out on Xbox 360, PlayStation 3, and PC on November 8.