I purchased a Zenbook UX31E on Saturday. I've installed Ubuntu 11.10 alongside Windows 7 for development needs. It's meant to be my mobile development laptop and so far it runs great. Obviously it has some quirks pointed out in reviews but I haven't had any issues I couldn't get past with updated drivers or configuration.

Ubuntu 11.10 is a battery hog, I think I can get about 4 hours out of the battery.

Windows 7 seems to estimate 5-6 hours.

I'd have to do further testing for actual hours on battery for both environments. So far, so good.