If you are looking for some introduction material to Microsoft Workflow Foundation 4.0 then here are a couple of links and tips.

Overview:

Windows Workflow Foundation (WF) Overview Wiki
http://social.technet.microsoft.com/wiki/contents/articles/windows-workflow-foundation-wf-overview-wiki.aspx

Videos:

Windows Workflow Foundation (WF) Screencasts:
http://msdn.microsoft.com/en-us/netframework/wf-screencasts.aspx

Endpoint TV screen cast:
http://channel9.msdn.com/shows/Endpoint/

Blogs:

Blogs that I follow for updates and development tips on WF 4.0

Andrew Zhu Blog - http://xhinker.com/

Ron Jacobs - http://blogs.msdn.com/b/rjacobs/

Unit Testing:

WF 4.0 is much more Unit Testing friendly. Ron Jacobs created WF 4.0 Unit Testing Helper library that is available at http://code.msdn.microsoft.com/wfth/

Forum:

Microsoft WF 4.0 Forum - http://social.msdn.microsoft.com/Forums/en/wfprerelease/threads

Using WF 4.0 with WCF 4.0 is one of the greatest experiences I have so far and one powerful toolset to know. These details should get you started with WF 4.0.

After you understand WF 4.0, I suggest you start looking at Microsoft AppFabric technology stack.

Cheerio!