Hyper-V MVP Aidan Finn has a post running over at http://www.aidanfinn.com/?p=17424 where he is maintaining a list of the new features coming in Windows Server vNext specifically around Hyper-V.
His post is worth keeping an eye on if you are in the Hyper-V virtualization business. Reading through it myself, there seems to be a lot of work gone into stabilising clustered Hyper-V which is very welcome. My personal favourites from the list so far are Production Checkpoints to allow you to checkpoint an application service; a number of VMs in a collection that make up an application such as SQL Server, an app server and a web server, all in a single operation for consistent snapshots across multiple service tiers. Network Adapter Identification allows the name of a vNIC from the Hyper-V host to be passed through into the VM Guest OS so our Guest OS will see our vNICs not as Ethernet or Local Area Connection but as Production-VMNetwork or whatever you naming convention is. Rolling Cluster Upgrades is something which Windows Failover Clustering has long needed to allow us to upgrade our nodes whilst retaining the cluster functionality and integrated Backup Change Tracking prevents the need for 3rd party backup APIs to be installed which can commonly destabilise the platform.
All in all, it’s a nice list of features and the changes will be very welcome. There is nothing here which technically blows your mind like the feature gap bridged from Windows Server 2008 R2 Hyper-V to Windows Server 2012 R2 Hyper-V however there is definitely enough here to pip your interest and to make you warrant moving to Windows Server vNext when it ships if only for the platform stability improvements.