Earlier today i read this news post on IGN.COM (all credit goes to IGN) apparently bungie is showing of halo 3 at seattle, WA tonight (Aug 21) at 10 p.m. PDT
People who attend will be shown co-op campaign demo and a selection of saved multiplayer game films on a big screen
i forgot to tell no one under 18 is allowed and no cameras neither
to know more on the news visit : http://xbox360.ign.com/articles/814/814285p1.html
again credit goes to IGN.COM for revealing this