While there are many good examples of .NET 3.0 within the Windows SDK, DinnerNow is a great example of how you can use all 4 components of the .NET 3.0 framework -- WCF, WF, WPF and CardSpace, and other technologies such as ASP.NET AJAX, PowerShell and the .NET compact framework. In addition to downloading source code, you can find labs and best practices. This sample application was put together by several Microsoft DPE members and has been used in many internal training and discussion sessions. Take a look at how the web application works at http://www.dinnernow.net