I have been getting more and more questions about how to use the Hyper-V v2 WMI namespace recently – so I have just created a TechNet Wiki article that links to a number of samples / documentation pages about how to do this.  You can get all the details here:

http://social.technet.microsoft.com/wiki/contents/articles/19192.hyper-v-wmi-v2-porting-guide.aspx

Cheers,
Ben