Asus plans to bring out a variety of configurations and Intel i3, i5 and i7 models are on the cards.
Closing the lid puts the Asus to sleep, and opening it again saw Windows resume at the login screen in 3 to 4 seconds.
If this story sound familiar, you may have guessed that this fast resume behaviour is already present in Apple's MacBook Air. In fact the MacBook Air is an Ultrabook. The 2011 models also use Intel Sandy Bridge processors similar to those in the new Windows Ultrabooks.
Indeed there are obvious similarities between the MacBook Air's design and the appearance of the Asus X31 - the metallic chassis, the recessed keyboard with separated keys, the vacuous space in front of the keyboard, the large trackpad, tapered thickness and the positioning of ports on each side.