There have been rumours that we'll see a Call of Duty: Modern Warfare 3 this year, and it seems like we will be getting more information about it soon. In the next issue of the Official Playstation Magazine there's a page with a large number three on it, with the text "the biggest game in the world returns", which is followed by a teaser of the following issue of the magazine - which incidentally is out on June 8, right in the middle of this year's E3.
We will of course keep you updated with any information about the game as soon as we have it.