I was just getting caught up on email and realized that the XAML Schema for WF has been published. Among the benefits here is that you'll get intellisense now in Visual Studio.
This was something that I know several customers expressed interest in, so I wanted to make sure everyone knew where it was.
You can find it here:
http://wf.netfx3.com/blogs/news_and_announcements/archive/2007/01/30/xaml-schema-for-wf-published.aspx