Have you checked out http://www.seewindowsvista.com/???
It is a very cool way to see some amazing things that developers are doing with Vista and .NET Framework 3.0. The site is clearly focused at end-users, but as a developer you might want to know what technology bets it took to make those apps.. I did a little poking around and here is what I was able to find out.... If there is some specific showcase you’d like to find more about please let me know.
Allscripts Healthcare: WPF
British Library: WPF
North Face: WPF
Otto Group: WPF, WCF, InfoCard, ClickOnce
90 Degree Software: WPF and WCF
Sourcecode (K2.NET): WF, WCF, WPF
Mike talks a bit more about these as well