I know the topics a little dead, but the article wasn't talking about Brutes being in multiplayer, it was talking about the Invincibility power up being a rare find in multiplayer matches. Brutes could be a potentially neat option, but if they were planning on putting them in multiplayer, Bungie would've said something by now. They wouldn't take the risk of adding them in and not telling anyone because Bungie knows that fan feedback is what has driven alot of the improvements and add ons to Halo 3 Multiplayer. Besides, if enough people got the game and decided they wanted to be a Brute in multiplayer, Bungie could(possibly) make a patch that you could download to add them in.
yeah months ago they even said brutes will not be added in and even though I have heard talk of them being in MP it is just rumors with no source and Bungie nor any of their affiliates have even mentioned in the slightest at this
the elites on the other hand they have basically guarnteed to be in
Oh, most definitely, what with the extra armor and all. In Single player, you play the whole thing as the Master Chief. In Co-op, the second player plays as the Arbiter, and I think that when Arbiter is not available, they play as Johnson.