Pro WF: Windows Workflow in .NET 3.5

During my holidays, I started reading Pro WF: Windows Workflow in .NET 3.5, and I recommend it: it is very well written and focused. Haven't reached the more advanced part, but, for now, I am enjoying it. It is my first in-depth contact with WWF, so there are lots of thing I don't know and I am very curious to know everything there is to it!

Now, what I really miss is a chapter on SharePoint workflows! :-(