Those of you still wanting to mod private matches etc can just replace the iw4mp in your MW2 folder (Program Files/Steam/steamapps/common/modern warfare 2) with the old 1.2.208 one and you can use MW2 Liberation with that.
The most funny is:
In BO they have added a "function" that allows us to use mods.
On Mw2 They now prevented that..
Isn't that a big fail?
Not really. Infinity Ward thought that mods ruined the game. After they released the game they realized there decision was wrong but it was too late to do anything about it, and Treyarch capitalized on this. Good thing though is that MW3 will probably allow mods like in BO.