Posters Name: Anthos
Posters Email: firstname.lastname@example.org
Subject: Valve looking for testers
Doesn't seem to be any game in particular in mind. Just if you want to be considered as a beta tester for any future Valve progams. Check out GameSpot's word on it here. Also, go directly to Valve's Beta Test page.
Source: GameSpot (http://gamespot.com)