We just published some new whitepapers discussing high level concepts of .NET Framework 3.5 which I hope you will find useful.
This paper drills into each of the new features added in the .NET Framework in versions 3.0 and 3.5. It discusses ASP.NET AJAX, LINQ, WCF, WF, WPF and CardSpace.
This paper provides a high level overview of the Windows Communication Foundation technology. It describes the problem in communications that WCF addresses. It goes on to describe the implementation of a WCF service and a WCF client and also introduces other aspects of WCF such as security, transactions, rest, syndication and extensibility.
This paper provides a high level overview of the Windows Workflow Foundation technology. It describes the problems in building applications that WF solves. If gives an overview of the components of Windows Workflow Foundation including sequential workflows, state machine workflows, creating and modifying workflows, creating activities, using rules, hosting the workflow runtime, tracking and modifying running workflows. It also provides a good comparison between this new technology and other existing process related Microsoft technologies.
This paper discusses the merits of considering SOAP and REST and alternative communication protocols between client and server. It describes how WCF supports these and many other communication styles with a single API through the simple ABC's (Address, Binding and Contract) of communications.