Steam+Linux - Would I need to buy one or two copies?

[pxc]

If you purchase directly from Frictional, you get all three versions (PC Mac and Linux). If you purchase from steam, I'm quite sure you only get the PC and Mac versions.

Excellent. Now the only question that remains is if I can register the copy from Frictional with Steam (for convenience). Whenever I buy a boxed game (or with some online purchases), I look to see if I can associate the game with my Steam account, since it manages most of my games anyway. I guess I'll give it a go, and post my results here.

Thanks, mate. :-)