I am working in Visual Studio 2010 Beta 2 with Windows Workflow Foundation 4.0. Generally speaking, it is a little easier to get around, the designer is more straightforward, the samples are fairly complete but documentation is lacking in some areas.
There is also very little by way of best practices, and I haven’t fully explored the pros/cons of the samples that Microsoft has put forward, but I am working through them and trying to get my head around this space.
Here are some sites that can help you get started:
I highly recommend the samples if you’re interested in WF; if you’re running Visual Studio 2010 they all load/compile relatively easily and some of the examples are fairly comprehensive.
As a tip, make sure you compile the application prior to loading the WF designers in the samples. I have crashed VS.NET’s designer and hung the IDE once so far by trying to drill in prior to compilation.