[tree_of_item]

Steam shouldn't be a problem for people who use free software: just don't buy software from Steam, same as always.

If Steam convinces more people to install GNU/Linux I'd say that's a net win. People are going to be using nonfree software anyway, so they might as well do it on a free operating system.

[icebraining]

Yes. And hopefully it'll add more pressure (and possibly help) to improve graphic card drivers and such.

[Laremere]

It already has. Their work on getting L4D working on Linux has already made it so that it now runs faster on the same hardware than with Windows. Source: http://blogs.valvesoftware.com/linux/faster-zombies/