There had been hints and screenshots back in April, but nothing official. Valve started an official Steam for Linux blog today that confirmed they've got a mostly-functional Steam client running and that their current goal is to get L4D2 running on Ubuntu 12.04 as well as it does on Windows. Considering Ubuntu 12.10 comes out in 3 months, we might be seeing Steam on Linux very soon.
Since there's already plenty of Steam games that have Linux ports (e.g. Humble Indie Bundle games), I wonder how long it'll be 'til the Linux Steam client boasts a decent library of games?
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