I just started developing my brand new windows 8 application last week using mvvm light.I am familiar with mvvmlight WP7 navigation. How i can achieve the same in windows 8.
Read the article published in MSDN Magazine just recently by Laurent Bugnion himself on working with the MVVM Light Toolkit and Windows 8.
Towards the end of the article he explains exactly how to setup the NavigationService you need.
NavigationService
http://msdn.microsoft.com/en-us/magazine/jj651572.aspx