Cisco publicly announced today that the Nexus 1000 and other Cisco technologies are coming to Windows Server 8 Hyper-V.

Here:

http://www.cisco.com/en/US/netsol/ns1154/index.html

and here:

http://www.cisco.com/en/US/solutions/collateral/ns340/ns517/ns224/ns955/ns963/solution_overview_c22-687087.html