One of the most frequent feedbacks the .Net services got about WF in the .Net services was why do you use WF 3.5 and not WF 4.0? So they won't. The .Net services will use WF 4.0 but they cannot do that until WF ships (22 March 2010) so until then WF was simply removed. Here is the formal announcement . Let us wait. There is no doubt that this was the right thing to do.