Microsoft - keep your filthy hands off Valve, leak shows MSFT would buy Valve
(www.gamingonlinux.com)
Yeah, I doubt he cares about the money at this point, and he did leave MSFT, so I'm guessing he isn't interested in selling. He also went out of his way to use Linux to stick it to MSFT.
As long as he runs the company, I don't see it happening.