A new feature in .NET 3.5 is the System.IO.Pipes namespace.  You can use this to created anonymous or named pipes between processes.  You could do the same thing with WCF, so I'm going to go through a series of screencasts to let you see the new features and then look at how you would accomplish similar things using WCF. 

The first video in the series looks at anonymous pipes.  Very primitive and most people will probably use named pipes, but its best to start with the basics. And perhaps you will have a scenario where anonymous pipes works for you.  This screencast is pretty much a rehash of what you find in the docs, but sometimes watching is more fun that skipping between pages in Help.

You can also download the Anonymous Pipes demo, and see other Spaghetti Code screencasts and videos here.