With Forge World and a massive amount of other customization options that have been revealed and exposed surrounding Halo Reach, it is quite clear why MLG would be utilizing these options as soon as possible. For those who are unaware MLG stands for Major League Gaming, and they have specialized in competitive Halo tournaments for the last 10 years.
MLG has always used the latest Bungie iteration as there flagship competitive console title. Bungie over the years has done an excellent job with blending community feedback and solid gameplay to make for the best competitive play possible.
These options have been limited until now. With the reveal of Forge 2.0 game customization has just become infinite, this is great business if you are a competitive halo player. MLG clearly has been working with Bungie prior to the games release due to there recent announcement that all tournaments starting in October would start to feature Reach in amateur and exhibition gameplay. All major tournaments this season involving major prize money and the main pro circuit will finish out using Halo 3.
It will be interesting to see if MLG goes back to its roots with class Halo 1 and 2 maps. Will they use armor abilities? So many questions will be answered sooner then later. After all this is the first time the MLG will begin using a new Halo title mid season, clearly there is something that just cant wait.