Game Informer were first in line with the responses from Infinity Ward, with this peculiarly unpleasant article by Adam Biessener. The Game Informer writer says of the general outcry about the news that MW2 would not support dedicated servers for online play: "Predictably, nerds across world took to the Internet with a wailing and a gnashing of teeth that would make the Left 4 Dead community proud." Or perhaps we - nerds or otherwise - were justifiably upset about a change to a proven way of doing things, a change no-one seems confident will be to our advantage. The article goes on to quote Infinity Ward's Jason West saying ""We're just prioritizing the player experience above the modders and the tuners... we thought maybe it would be cool if the fans could play the game."
There's a more detailed breakdown of what IW are proposing over on Robert Bowling's blog, which makes for a clearer response. I'm a little dubious about the anti-cheating claim, however, since dedicated server admins have gone a long way to self-policing the community, and I feel like IW's claim that they'll be able to deal with it might be a little bold.