Some good resources if you are just getting started with WindowsWorkflowFoundation
The WindowsWorkflowFoundation team has released a large number of samples along with the first version of the product. You can download them from http://go.microsoft.com/fwlink/?LinkId=73348.
The Microsoft run community site at: http://wf.netfx3.com. This sides includes lots of information but quite a bit of it is about older bits and the changes make these older demos incompatible with the current RC version.
AngelLopez has compiled a list of resources in this blog post: http://ajlopez.wordpress.com/2006/10/09/learning-windows-workflow-foundation
MichaelStiefel did four interesting shows for DnrTV:
MikeTaulty did a whole series of short videos about WF in the MSDN Nuggets series
Daniel Karlsson's blogg om workflow foundation på Svenska