The probably just "borrowed" Bliazzard's Warden softare which sends them a list of processes that are running on your machine, as well as information on any open windows, includng email and IM addresses. Not much better than a rootkit, as it's a MAJOR invasion of privacy (which is why I don't and won't ever play WoW) If I, for example am running a program called hotsexforcavedude.exe and am talking to cavedudesloveslave on AIM, I don't want them knowing that. Though ironically enough, Warden has been bypassed using Sony's rootkit.
http://games.ninemsn.com.au/article.aspx?id=71153