The .NET Framework 3.0 RC1 has been released:
.NET Framework 3.0 RC1 (containing Workflow Foundation RC5) http://www.microsoft.com/downloads/details.aspx?FamilyId=19E21845-F5E3-4387-95FF-66788825C1AF&displaylang=en
VS Extensions for Workflow Foundation RC5 http://www.microsoft.com/downloads/details.aspx?FamilyId=117ECFD3-98AD-4D67-87D2-E95A8407FA86&displaylang=en
Windows Vista RC1 SDK (optional: provides SDK samples and help) http://www.microsoft.com/downloads/details.aspx?FamilyId=117ECFD3-98AD-4D67-87D2-E95A8407FA86&displaylang=en