I am a massive fan of professional Halo. Massive. One of my first gigs as a writer was for Major League Gaming, before it was the Starcraft juggernaut it has become today. So I'm beyond delighted to see that MLG has decided to continue supporting Halo, but featuring a Halo 4 tournament at its Fall Tournament in November -- before the game has even been released to the public!
As evidenced by videos released on YouTube, some of the top pros have already spent a fair amount of time with Halo 4's multiplayer, so I'm hoping they all manage to get enough practice to actually put together a proper competitive tournament.
My main worry would be that MLG themselves may not have enough time with the game to put together some truly competitive settings. Usually the first year of a game's competitive lifespan is the worst, as players get to grips with new features, new maps, and new weapon balance, so the idea of having a competitive tournament before the game is released to the public? That could raise a few problems.
Regardless of that one quibble, this is a pretty big deal for the Halo pro community -- there was a worry that the game may be left by the wayside as a result of its declining popularity. MLG has had a lot of success by focusing on PC titles recently, but I'm happy to see MLG staying true to its roots and supporting the players and the community that helped it get to where it is today.