I had posted something along the same idea. We need a WAR chat and a WORLD chat. Both can be used for recruiting in game, or just talking smack. I love the idea of both.
I agree that a world chat would be awesome! I was thinking a "war chat" tab next to the existing alliance chat. Important: Players should have the option to "OPT IN" on both chats. So basically. players would have the choice of seeing the other alliance comments are not.