Microsoft offers Application Virtualization (formerly SoftGrid) and soon Enterprise Desktop Virtualization (formerly Kidaro Managed Workspaces) only through a special bundle called Microsoft Desktop Optimization Pack (MDOP).
The offering is peculiar because the MDOP is only available for those customers which agree to buy the Microsoft Software Assurance: a 3-years deal which allows to receive the newest version of a certain product without paying the software as brand new.
Obviously the Software Assurance comes as a premium service which some customers are not happy to pay.
Over the last two years virtualization.info collected a number of complains about the way MDOP is offered, and a superficial search on the Internet will return enough clarifications that a SMB company with no more than 50 desktops can't consider the Software Assurance as the right option to go.