If you're wondering where Co-op Exfiltration is on Ghost Recon Advanced Warfighter 2, this post on Ubi forums from Christine Allen, Creative Director of GRAW2 Xbox 360 Online clears it up.
"No, no big conspiracies. I PM'd Kleansy earlier, but I forgot she is on UK time. Co-Op Exfiltration is a game mode that we were working on late in the dev process for possible future inclusion in DLC or another platform of the game. We have so many game modes that this description accidentally leaked into the blog. So now you have a sneak peak of some things possibly to come. Hope that clears things up; and players enjoy the hundreds of other co-op game mode combinations available in GRAW2."