Q u o t e:
so i was handing in the quest [Alert Our Leaders] and when you talk to Garrosh it says

<The warchief listens as you tell of your investigation into the Twilight's Hammer plot to destroy Orgrimmar>
You are a dutiful member.. bla bla bla....


so does this mean he is the warchief already?

Garrosh has recently been handed the position. I'd say more, but I don't want to spoiler things in game. It might be a good idea to hang out in Grommash Hold for a bit just to listen in on what the leaders have been discussing. In addition, you may want to check out the new novel that was released (written by Christie Golden) The Shattering: A Prelude to Cataclysm to learn even more (if you are interested in doing so.)