It's is a replacement for IWnet. Basically a MW2 private server, which you can hack on, but you can still get banned on it. But as far as i know, you can get unbanned from it.
lol yea, its this
it has its own mod spot when u click find game, thats where u test ur mods, or u can test in private match, and with getting banned on aiw all u have to do (so im told) is change ur mac address, which just really isnt that hard :P