Hi Mahesh,
Virtualization is a wide topic. In the world of computers we need the resources to work such as Machines, Harddrives, Servers, Routers, Printers, etc., which will cost a lot to have the physical units. The Virtualization mades this resources available virtually to the application and made that to work proper. (a kind of Simulation)
We can highlight some of them
1. Platform Virtualization
2. Resource Virtualization
3. Application Virtualization
4. Desktop Virtualization
5. A lot more........
Microsoft has lot of Virtualization Implementation, Virtual PC is an example. Currently they are working on the Server Virtualization and there is a dedicated forum available for that
http://social.msdn.microsoft.com/Forums/en-US/servervirtualization/thread/9d129a49-be90-43f2-b94c-d5c2576155fe/The Hyper-V is also microsoft product under server virtualization, you can get the information about Microsoft.com Operations Virtualization of MSDN and TechNet on Hyper-V in the following link.
http://download.microsoft.com/download/6/C/5/6C559B56-8556-4097-8C81-2D4E762CD48E/MSCOM_Virtualizes_MSDN_TechNet_on_Hyper-V.docxThanks,
Vijay Pandurangan.