Looks like Windows 8’s new Metro style will not be the only user interface option. There will still be the traditional desktop, but it will not start up by default. Instead, it will launch like any other application. With this, you wont be wasting system resources if you care to only stick in the metro interface (on a mobile, or tablet for example). This should hopefully put to bed all the worry worts out there about Windows 8 only running javascript+html5 apps. There is a real OS behind it all folks, your current xp/vista/windows 7 applications will continue to function.
If you would like to read the msdn blog post, you can catch it here: http://blogs.msdn.com/b/b8/archive/2011/08/31/designing-for-metro-style-and-the-desktop.aspx