At least 2 map packs announced

[UPDATED] After selling 8 million map pack units for Call of Duty 4: Modern Warfare this time Modern Warfare 2 will get two map packs. 

During the E3 2009, Activision announced that Microsoft will get two Call of Duty: Modern Warfare 2 map packs exclusive for the Xbox 360 for a limited time. Later these will also be released as downloadable content for the PS3, nothing has been said about if PC will join the party or not (but it is unlikely).  

While discussing Activision Blizzard's financial figures yesterday, Activision CEO Mike Griffith spoke about the downloadable content gamers can expect for Modern Warfare 2.

"We already plan on two different map packs for this title to be issued," said Griffith on the DLC. "Map packs help extend the shelf life of the franchise, as evidence by the strong catalog sales and premium pricing that we maintained a year and a half after launch.", said Griffith. "Until now we have always had great success with map packs within this franchise." This might be a small understatement since  he continued: "To date, we've had strong success with map packs on this franchise, selling more than 8 million units for both Xbox 360 and PlayStation 3."

You don't have to be good in math to realize that selling another 8 million units à $10 will be good for business... 

[UPDATE] Robert Bowling makes it very clear there could be more than two map packs, the amount would depend on the wishes of the community: 

As far as DLC goes, we love it and plan to support 'Modern Warfare 2' heavily with post-launch support. We’ve confirmed we’ll be doing AT LEAST two map packs which were announced at E3 as a timed exclusive for Xbox 360. The fact that we confirmed at least two map packs doesn’t mean there won’t be more; honestly we plan on shaping our DLC based on community feedback from the full game, and first two DLC map packs. Therefore, the community will really determine what comes after that.

Thanks XAL from our MW24/7 forums!