A lot of people don't realize that Citrix XenDesktop supports more than XenServer as a backend.
In fact, it will support any backend infrastructure (or infrastructure-less) environment that has a plug-in. XenDesktop ships with plug-ins for XenServer (of course), SCVMM, and Virtual Center.
Since most folks don't know that SCVMM support is available I took some time to put a little something together. I even have my VMs running on Hyper-V.
One caveot, your XenDesktop Desktop Delivery Controller Server must be 32-bit.