I've had this sitting in my inbox for a while now, so I thought I would share it:

"This topic discusses how SAN transfers work in Virtual Machine Manager (VMM) and how to configure your system for VMM to work in a SAN environment. You can deploy VMM in an environment that has either a Fibre Channel or an iSCSI storage area network (SAN) and perform SAN transfers within VMM"

Check out the full lowdown here: http://technet.microsoft.com/en-us/library/bb740748.aspx