[chadillac]

not technically an Ultra book but I've been a huge fan of the Thinkpad X series for sometime.

Currently have an X220, works great, the X1 is also nice and some of the Ideapads are more "consumer grade" but would fit nicely into the "Ultra Book" territory. With Thinkpads you never really (or I haven't ever) run into issues with *nix due to the amount of love they seem to garnish from the tech community in general.

Between the cozy keyboard and the overall durability of the Thinkpad line I keep coming back to them year after year.

[hbien]

I'll second this. I'm currently using the X220 with Gentoo and it works perfectly except for the trackpad (which shakes the cursor in some areas). I have to use the keyboard mouse pointer. I was also concerned about price and managed to get mine used on Craigslist.