These toys are not for sale, those lucky developers attending BUILD were given one free!
Another write up which includes pictures can be seen here courtesy of Neowin.
Core i5 processor
4GB of DDR3 RAM
64GB SSD hard drive
Wifi and 3G
11.6-inch Super PLS 1366-by-768 display
Punchy spec's, only drawback is that it weighs 2 pounds and won't be retailing near you soon, but those that got their hands on one gets some KICK ASS hardware for their trouble. The article says these won't be retailing, its more a tool for developers to use for debugging Windows 8 applications.
Read the complete post at http://wmug.co.uk/blogs/r0b/archive/2011/09/14/windows-8-cough-tablet.aspx