Mi era sfuggito (e comunque è on line da poco) ma lo trovo un progetto molto molto interessante. L'abstract, su CodePlex, recita:
"This project provides windows workflow activities to create WCF services using windows workflow foundation. These activities are similar to the out of the box activities provided by microsoft for ASMX webservice implementation in workflow. The initial code drop will include a WCFInput and a WCFOutput activity that have similar functionality as the current ASMX implementation."
Molto interessante 
. Qui tutte le info