Lenovo LaVie Z

This laptop (HZ550), just announced last week at CES (Consumer Electronics Show), won't be available until May, is pretty sweet at 1.72 pounds, making it more than a pound lighter than its 13" MacBook Air competition.  Expect to pay 3-4 times that of a decent laptop.

http://news.lenovo.com/article_display.cfm?article_id=1878