Where Windows 7 includes the software-based virtualization solution called Windows Virtual PC, Windows 8 will usher in a new era with a true hypervisor-based virtualization platform called Client Hyper-V. Virtually (ahem) identical to the Windows Server 8-based Hyper-V 3.0, Client Hyper-V utilizes the same Hyper-V Manager user experience and offers dramatic performance, scalability, and compatibility improvements over Windows Virtual PC. It's night and day, folks. Night and day.
Here are some shots of Hyper-V Manager running in the Windows 8 Developer Preview. Note that this feature is optional and is not installed by default. As with Windows 7, you install optional features from the Windows Features (classic) control panel.