Most likely, if you look upon Bungie's Halo 3 forum, you will find requests for more than just two player models in multiplayer. Everybody yearning to play as a Grunt or Combat form or Jackal. And it's no surprise that Bungie, the game-makers famous for listening to their players have once again taken pity on these player's desperate pleas. As of June 3, Sentinels, Halo 3's robotic cleanfreaks, are going to be joining the ranks of multiplayer.
Sentinels are very unique in multiplayer in that they can fly. They also have an equipped sentinel beam with a recharging battery. They are, however, unable to pick up weapons or throw grenades, and they cannot hold flags or any other objects. When asked if this will unbalance gameplay, a Bungie employee replied, quote: "We wouldn't be anywhere without the fans, if the fans want it, we want it. It makes the fans happy, so we're happy, and that's all that matters."
Sentinel Players will be able to color the Sentinels in steel, aluminum, titanium, and silver colors and display the insignia of the Installation of their choice. This will let players express their creativity while keeping within the realms of canon.
That's all the information we can certify at this point, but if there's an update, you know you'll here it, nothing but the facts, first thing, from your very own Lockout Weekly