Gabe over at Penny Arcade has posted that this month's Gaming Day event, to be held at Lanwerx in Bellevue, WA on August 23, is going to feature a Halo tournament as well as some Halo 2 stuff:

To go along with our Halo tourney, Microsoft will has agreed to come down and show off a bit of Halo 2. We aren't sure yet if it will be the same stuff they showed at E3 or something new but either way it's pretty fucking exciting.

Penny Arcade, of course, is a regular webcomic focusing on gaming that has, at times, mentioned Halo in the past.

More details about the tourney are expected on Friday.