There's a simple reason that ASUS's ultrabook entry has proved the most elusive at this year's IFA tradeshow: the prototype that debuted at Computex in May has since conked out. The 11.6-inch UX21 machine I finally tracked down wasn't a working model, and had clearly been through the ringer (no, those scratches on the lid aren't a feature). Still, while I wasn't able to turn it on, I was impressed with the build quality of the machine. It's pure aluminum, and I wouldn't be surprised if the TSA eventually decides it's a weapon -- it's heavy and tapered enough. There's zero flex to the screen, and the hinge is reassuringly solid. The keyboard isn't my favorite, however: the keys have shallow travel and mushy springs. Of course I couldn't use the trackpad, but it's nice and large and made of glass. One thing worth noting is that while the UX21 is one of the thinnest laptops I've ever held, it's also challenging the MacBook Air in terms of port stingyness. There's no SD card slot, and the HDMI and DisplayPort are both the of the mini variety.

If 11.6-inch isn't your jam, there's good news: ASUS is also prepping (surprise!) a 13.3-inch version of the ultrabook, dubbed the UX31. It's just as thin as the UX21, at 0.67-inches, and seems to be nearly identical on the spec front, with 2nd gen Core i7 and Core i5 processors, 2 second sleep resume, and 10 days of standby (for comparison, Acer claims to have 1.5 second resume, and 50 days of standby). The UX31 weighs 2.9 pounds, compared to the UX21's 2.4 -- both of the laptops are pretty hefty for the ultrabook category.

Hopefully the UX21 and UX31 will both land as expected in September with the majority of these ultrabooks -- ASUS is sounding very aggressive on price, and we're looking forward to a world where a $799 ultrabook is a reality, not just a beautiful dream. Hands-on shots of the UX21 are after the break (the UX31 was only a placard), and if you want to see the UX21 go head-to-head with the MacBook Air, that can also be arranged.