Microsoft has just announced that gamers will be able to sign up to participate in the Halo 3 multiplayer beta on Monday, December 4. On that day, people will be able to sign up for the beta by going to www.halo3.com; those gamers selected will get exclusive access to the pre-release code some time around spring of 2007. The sign-up is tied to the debut of a new CGI-rendered trailer for the game set to air on ESPN’s Monday Night Football between 5:50 and 6:20 p.m. PST.