Well, there is some benchmarks, but again, there would be no point in "1 fps vs 2 fps" benchmarks, you want some 1.5D benchmarks, that would ran higher than 1 fps on intel graphics ? . And releasing steam on linux doesnt mean much, look at mac, how long it has steam and how "big" it is.
Actually it does mean much, namely that Valve considers Linux to be a viable gaming platform that pulls in enough revenue to get back development/porting costs. Not to think about that Valve announced the Steambox to be Linux based, which would be a funny move if they consider Linux not to be a gaming platform. The same is true for Blizzard, announcing a MMORPG with a Linux client (again, they wouldn't do that if they wouldn't think the money is well spent) or Dell/Alienware selling Linux gaming systems.