If you are running multiple hypervisors in your data center and are tired of managing the mix, then perhaps you might want to look at a new entrant in the field called HotLink SuperVisor. It provides system management of heterogeneous virtual computing and supports all major hypervisors including VMware vSphere, Microsoft Hyper-V, Citrix XenServer and Red Hat Enterprise Linux. What this means is that you can choose your management console, such as vCenter, and have it manage multiple hypervisors (other than VMware) using the glue that Hotlink provides to connect the two. You VMs are still running on the original hypervisors, but you can manage everything from one console. You can also migrate your VMs to other hypervisors too if you so desire.
The VMware version is the first product, and is in beta and will be out by the end of the month. It will support XenServer, Hyper-V and Linux KVM hypervisors. Pricing starts at $25,000 for the supervisor platform, and that includes support for one addition hypervisor and five concurrent hosts. Obviously Hotlink has adopted the VMware pricing model of making things as confusing as possible. They do have current customers who claim the mix and match policy has had dramatic paybacks, since you forgo licensing of the different management consoles.
Hotlink isn't the only one that can migrate VMs among hypervisors: this has been possible with various open virtual formats for years, and products such as Sun/Oracle's Virtual Box can read in VMware and Xen VMs for example. And Xen has had the ability to manage both its own and Hyper-V infrastructure, but it is done with two different software versions of the management console.