We got Halo Reach in a silver briefcase today. I took it to the roof for an unbriefcasing video, guest-starring the distant Empire State Building and a blimp. This is really just the standard edition plus doodads plus briefcase.
You can't buy the briefcase edition, because it's just a mailing method for press, to get them to post unbriefcasing videos or something. Halo Reach will be released officially next week. We'll have a review over the weekend.