There's a new screencast series on building services using the WCF part of .NET.
The first few are already available. The first one is the basic "Hello World" example, the next couple cover REST:
How to build a WCF Service using Visual Studio 2008, and .NET 3.5. (10 minutes)
Creating a HI-REST GET Service with WCF 3.5 sp1 (15 minutes)
Consuming a HI-REST GET Service From Silverlight 2 (Beta 2)
How to Shape the URI in REST services built on WCF (See also, the accompanying blog post.)
There will be more to come, too, covering Content Negotiation, Atom, and more. Stay tuned!