The WCF Hands On book started off as WCF Labs for last years PDC. We started writing it last year, when the docs were pretty sparse in places (as one would expect).
I haven't spent alot of time in the help file until this morning. I'm updating the chapter of the book that deals with COM Interop and needed to double-check something. I shouldn't have been surprised as we're much closer to RTM, but it was *much* more complete and has lots of good info and downloadable samples. There If you haven't look at the doc (or the samples) lately, I'd definately recommend revisiting them - there's also a good POX sample in the RC1 drop as well.
If you want the absolute latest public drop of docs, there was one made on September 15th. It's posted over on netfx3, check it out here:
http://wcf.netfx3.com/files/folders/product_team/entry5854.aspx
