Not only is the Mohawk Grenade real and in-game, but Mr. T put it there. That's what we learn in this new commercial, a sequel of sorts to the old "Night Elf Mohawk" joke a long while back. Not only is T (not The T, just T) decked out in a Murloco's Taco's T-shirt, but he shows the in-game item in action. It's how he makes the World of Warcraft look good.
I love it -- well done, Blizzard. Great kickoff to the holiday marketing season, and it's awesome that they've got the commercial (which we assume you'll soon see on television) promoting the actual in-game item in a quality way. Sure, The Old Republic and a few other MMOs might be knocking on WoW's door, but who wouldn't want to play a game where you can throw a grenade and make people look like Mr. T? Maybe this is where all those newbies will be coming from.
World of Warcraft: Cataclysm will destroy Azeroth as we know it. Nothing will be the same. In WoW.com's Guide to Cataclysm you can find out everything you need to know about WoW's third expansion. From Goblins and Worgens to Mastery and Guild changes, it's all there for your cataclysmic enjoyment.