Which also seems to have very good hardware support: https://help.ubuntu.com/community/MacBookAir4-2

I think 4-2 is the 2011 Macbook Air. I've been thinking about getting the 2012 and putting Ubuntu on there, but there seem to be a number of semi-unsupported steps required to resolve kernel panics, you have to disable apic support and various other issues.

I regret that there's no good documentation for installing on the 5-2 (2012 13" Air), something I have to take some responsibility for since I run Ubuntu on such a laptop and didn't share my experiences.

In short, most things work fine on Ubuntu 12.10. I first tried using this guide[1] to install Ubuntu 12.04, but had lots of gnarly install issues. I then tried with the regular 'amd64+mac' graphical installer for Ubuntu 12.10 beta, and got it running easily. I was able to ignore most of [1] except for installing and configuring macfanctld, and making the touchpad perform decently using the advice in [2]. (Unlike the author of [2], I hate tap-to-click, so I turned the TapButton[1-3] settings off.)

There are still a few nagging issues I haven't fixed. The Air boots with brightness at the max and won't let me turn it down until logged in, and it loses my touchpad settings on reboot, so I have a little bash script I run to fix them.

[1]: http://ubuntuforums.org/showthread.php?t=2039799

[2]: http://uselessuseofcat.com/?p=74

For a much lower price, actually. $1140: http://www.amazon.com/Apple-MacBook-MD231LL-13-3-Inch-VERSIO...

Or $1430 (still over a hundred dollars less) with twice as big of an SSD: http://www.amazon.com/Apple-MacBook-MD232LL-13-3-Inch-VERSIO...

This XPS does have 8GB RAM (versus 4), but that's the only big advantage that sticks out to me.