[Update: A newer screenshot available on a more recent post]
Although Visual Studio 2005 and the appropriate extension can enable WPF development, with the release of beta 2 Visual Studio 2008 we have a seemless integration of Windows Presentation Foundation (WPF) application development to the IDE.
I am disappointed that we haven't seen more WPF apps out there. Having read a book on the new presentation framework that comes with every copy of Vista and can be downloaded for Windows XP, I wanted to see how quickly I could clone the Gmail interface. I like the Gmail interface, and it really demonstrates the power of AJAX. Nevertheless I suspect that Gmail is the product of many thousands of hours of work to make the interface what it is. How fast could a WPF application replicate that?
How about 4 hours?
In those four hours I got data-binding for the Inbox working along with the right layouts so that it resizes appropriately. The look isn't perfect yet, and there's only that opening screen that I have working so far. Four hours isn't enough to replicate the whole Gmail interface of course, but it's pretty amazing what can be done in such a short time!
When I've got more to show off, I'll try to publish the .xbap so you can try it out, and perhaps even the whole source code as a working sample.