Why's Portal being released on Xbox Live Arcade? Valve say it's to give people who otherwise missed it a chance to catch up, see what all the fuss is about. When asked by OXM whether that meant other Valve games might be seeing a similar release, Doug Lombardi responded:
We'll certainly consider it. If you look at what we've done on Steam, we try to make all our games available and we're always reviewing the prices to keep them current. We'd love to do that, but Portal: Still Alive is our first step at doing that beyond the PC.
First step, but probably not the last. Valve love money as much as the rest of us.
Counter-Strike on XBLA? [OXM, via CVG]