Out of what little we know of the next version of Windows, this feature might just be the most interesting yet. A team at Microsoft is hiring developers to work on adding native support in Windows 7 for Virtual Hard Disks (VHD) - Microsoft’s semi-proprietary specification for single-file virtual machine hard disks.
Their job posting reads:
Do you want to join the team that is bringing virtualization into the mainstream? In Windows 7, our team will be responsible for creating, mounting, performing I/O on, and dismounting VHDs (virtual hard disks) natively. Imagine being able to mount a VHD on any Windows machine, do some offline servicing and then boot from that same VHD. Or perhaps, taking an existing VHD you currently use within Virtual Server and boost performance by booting natively from it.
Link: iStartedSomething