The Ultrabook is a concept from Intel which brings the Macbook Air like design to the PC world. Asus is getting prepared to launch their first Ultrabook and according to their Facebook Page it may be on October 11th.
Ultrabooks like the UX21 will finally bring a MacBook Air competitive design to the Windows platform. The Asus Facebook page points towards an event in New York on October 11 and an Asus website which says "Good Things come to those who wait" with a picture and reference to an Ultrabook, along with a counter counting down towards the said date.
The Asus Ultrabook was also presented running Windows 8, when Microsoft released Windows 8 - Developer Preview. We know that Microsoft is far from ready to release Windows 8, so if the Ultrabook is launched on the 11th, it will probably be running Windows 7.
Since I am almost certain Asus will offer Ultrabook owners a Windows 8 upgrade, the general availabiliy of the Ultrabook from Asus may mark a date for free Windows 8 updates. Well one can at least hope.
source - Asus