Number One:

Microsoft announces that in SP1 for Windows Server 2008 R2 they will have Dynamic Memory Allocation. That’s nice, not always useful, but nice to have. So now you wonder when SP1 is about the come, right :-), sorry cant tell you that…
But meanwhile, you can read about it here
http://blogs.technet.com/virtualization/archive/2010/03/18/dynamic-memory-coming-to-hyper-v.aspx

The rest:

Well, the requirement for Virtual XP mode has changed, it does no longer require that the hardware has support for hardware assisted virtualization and that super nice, that means that more or less anyone can use Virtual XP mode (A part of Windows 7)

Next up, Remote FX, its a component that will be inside Hyper-V and what it does is provides the VM with accelerated graphics, you can now run Aero/Glass/Silverlight with full acceleration, pretty cool :-)
http://blogs.technet.com/virtualization/archive/2010/03/18/dynamic-memory-coming-to-hyper-v.aspx
http://www.virtualization.info/2008/01/microsoft-acquires-vdi-vendor-calista.html

A change in license is also being done. The separate license that was needed to run a Virtual Desktop is going away. That means that the cost for VDI will be lower, much lower. This will begin July 1, 2010

“Licensing model changes for virtual Windows desktops: Beginning July 1, 2010, Windows Client Software Assurance customers will no longer have to buy a separate license to access Windows in a VDI environment. In addition, on the roaming-rights front, as of July 1, 2010, Software Assurance customers and new Virtual Desktop Access customers will have rights to access their virtual Windows desktops and Office applications hosted via VDI on secondary, “non-corporate” network devices, like home PCs and kiosks”

Citrix & Microsoft are also working on enabling HDX in Citrix to work with Remote FX in Hyper-V. http://www.citrixandmicrosoft.com/

oh, right, also. MS has created a depth performance analyze around Hyper-V, you should read it. http://download.microsoft.com/download/0/7/7/0778C0BB-5281-4390-92CD-EC138A18F2F9/WS08_R2_VHD_Performance_WhitePaper.docx

/m