The news now coming out of the big Activision conference call now includes some about MW2. Shacknews reports that during the conference call Activision Publishing CEO Mike Griffith said "We plan to launch two separate map packs for this title."
Shacknews has interpreted this to mean that there will be only two DLC releases for MW2. What this means for PC is still completely speculation as well. The Map Packs were only discussed in terms of consoles once again.
http://www.shacknews.com/onearticle.x/59869