I'm impressed, will no doubt be back to 20 odd seconds once you've had your laptop for a month or two.
That's booting from a fresh installation on an SSD.
That will not be the standard experience.
The point is that it will be able to boot significantly faster than it would without hibernating the kernel session. Windows 7 still boots in about 30-40 seconds for me on a magnetic hard drive, and I've been running this build since it came out. Assuming Windows 8 boots faster to start with, and factor in the kernel hibernation then eight seconds on an SSD sounds perfectly achievable.
EDIT: After reading an earlier blog entry, it also looks like this super mega fast boot is only to the new, lighter Metro interface. The traditional desktop doesn't load unless you set it to boot to that, or load it from Metro.
I play games and mumble over them: http://www.youtube.com/user/Mogster2013