.NET 4.0 introduces the System.Windows.Shell namespace which makes it very easy for you to leverage the Windows 7 taskbar enhancements in your application such as:
Most of these features can literally be implemented in a line or two of .NET code or XAML. I wrote this brief white paper and downloadable sample project to demonstrate how easy it is to build this functionality with a mixture of imperative C# code and declarative XAML. The scenario is based on this simple CRM-like WPF application.
While these features are Windows 7 specific, using the .NET APIs your application will gracefully degrade on operating systems prior to Windows 7.