Microsoft has provided June CTP for .NET Framework 3.0. If you are interested in downloading these, here are the links
Microsoft Pre-Release Software Microsoft .NET Framework 3.0 - June 2006 CTP
Windows SDK for .NET Framework 3.0 June CTP
Microsoft® Visual Studio® 2005 Extensions for Windows Workflow Foundation RC2 - Provides developers with support for building workflow-enabled applications using Windows Workflow Foundation with the release version of .NET Framework 3.0.
Windows workflow Foundation RC0 labs - Windows Workflow Foundation RC Hands-on Labs, manuals and sample code
Microsoft Visual Studio Code Name “Orcas” Community Technology Preview – Development Tools for .NET Framework 3.0 - Provides developers with support for building .NET Framework applications using Visual Studio.
Time to play with Windows Workflow Foundation :)