That Indigo Book
Indigo is something to start learning - there's a lot to learn, so the sooner the better. Indigo is a set of .NET technologies for building and running connected systems, centered around the WS architecture, and is in essence a unification of Microsoft's distributed computing technologies.
Scott Seely is on the Indigo team, and is working with Brian Nantz on a new book on Indigo. You can read lots about Indigo over here, as well as find some of the chapters.