The Halo 3 Multiplayer Beta will go live on May 16th at 12:00 AM PDT and run through June 6 th at 11:59 PM PDT.
The Beta testing is accessible only to those who purchased specially marked copies of Crackdown, or won a spot in the Beta regional promotions or through the "Rule of Three" campaign which required users to register on Halo3.com, play three hours of Halo 2 between February 1st and February 3rd, 2007 and be one of the first 13,333 players to do so.
You can still enter the Beta by purchasing a specially marked copy of Crackdown.
The Beta itself consists of three maps - Valhalla, High Ground and Snowbound - graphically improved since their first screenshots - and all three will be playable in Matchmaking only. All three maps are suitable for a wide variety of gameplay types, and testers will have the chance to try all manner of game types, familiar and new.
There are a number of new features included in the Beta, including a new grenade type and a completely different class of weapon, but it should be noted, a lot of secret features are hidden in this Beta.