Microsoft will allow bass-ackwards XP-only applications, such as IE 6-only web apps, to run in emulation via Virtual PC as part of the regular Windows 7 desktop. That feature will apparently be standard in enterprise-class versions of Windows.
I appreciate that Microsoft has found a way to do what they have been unable to do for years: push a modern web browser onto the desktops of the most stubborn corporate and institutional clients. The people who make the lives of web designers pure hell by insisting on IE 6 compatibility because they once allowed someone to sell them a web application that can never, ever be upgraded to work with anything else. This is good. Frustrating as all hell, but good.
But Microsoft, if you do this the wrong way... where "the wrong way" is allowing admins to enforce a policy like "everybody gets virtualized IE6 all the time and may not have IE8 as their default browser..." then you're going to hear the screaming, the wailing and the gnashing all over again.