Well most of the issue I have with Linux is graphics compatibility, that being said, I'd recommend any with an nVidia GPU over one with an ATI one. With that you will certainly have a much better experience.
Nit-pick: the "Ultrabook" brand specifically means an Intel CPU with built-in GPU. Even outside the brand, there aren't many laptops with that form factor with a non-Intel GPU these days.
Having said that, for window compositing the open-source radeon drivers seem to work fine as long as you don't go for a bleeding-edge chip.[1] For games, the proprietary nvidia drivers are likely better and might be worth the extra hassle (but realistically, booting into Windows is less hassle and gives a bigger choice of games... Also, realistically, you won't get a powerful 3D chip in a thin & light laptop).
[1] I've never tried the open-source nouveau drivers for nvidia chips; they have apparently been improving in leaps and bounds.
"Ultrabook" currently specifically refers to a system with a Sandy Bridge or Ivy Bridge based ULV CPU, all of which have integrated on-die GPUs.
Re the announced system: interesting - does Optimus work on Linux these days then? Last time I checked, the GPU on Optimus systems was dormant on Linux.
On the other other (third?) hand, sometimes you want GPGPU which even in laptops can give some speedup, not to mention not having to debug it on large computer. With intel, you're out of luck there.
Read the ati support list before buying an still closed source driver board.
Nvidia may seem better because they only have close source drivers. Compare it with catalyst, and they are pretty much the same (except you will not get dual monitor easily with Nividia)
I have ATI cards in all my linux machines. They work /ok/, but it really seems like ATI only gives lipservice to being linux-friendly. After making promises for over a year about how big there commitment is, the improvement has been disappointing.
Having said that, for window compositing the open-source radeon drivers seem to work fine as long as you don't go for a bleeding-edge chip.[1] For games, the proprietary nvidia drivers are likely better and might be worth the extra hassle (but realistically, booting into Windows is less hassle and gives a bigger choice of games... Also, realistically, you won't get a powerful 3D chip in a thin & light laptop).
[1] I've never tried the open-source nouveau drivers for nvidia chips; they have apparently been improving in leaps and bounds.