Here is the latest in my link-listing series. Also check out my ASP.NET Tips, Tricks and Tutorials page for links to popular articles I've done myself in the past.
Visual Studio 2008 and .NET 3.5
Running 32-bit and 64-bit ASP.NET versions at the same time in different worker processes: With IIS6 you either had to run all web worker processes in 32-bit mode, or all of them in 64-bit mode. There was no easy way to mix and match depending on the application (you couldn't have one 32-bit ASP.NET application that needed to use a C++ component on the same machine as another 64-bit ASP.NET application in a separate application pool). With IIS 7.0 this is now supported and easy to enable. Rakki Muthukumar from Microsoft support describes how to configure this.
WPF and Silverlight
.NET 3.5 Add-In Model: Jack Gudenkauf is a developer on my team who has driven the design of the new System.AddIn namespace in .NET 3.5. This namespace makes it easier to build add-in extensibility to your client applications. Among other things, this enables you to isolate addins and WPF controls across application domain and process boundaries (here is a sample of one). Watch Jack's Channel9 video to learn more.
Data Binding in WPF: A nice MSDN Magazine article from John Papa that describes some of the basics of how WPF's binding model works. Josh Twist also has some good WPF databinding companion articles that complement this here and here. To learn WPF in more detail, I highly recommend Adam Nathan's excellent WPF Unleashed book (still 5 stars after 45 reviews on Amazon.com). The next public release of Silverlight 1.1 will support the same powerful databinding model that is in the full WPF, and will make building data aware applications much easier.
Hope this helps,