Today's $10 Deal of the Day from APress at http://www.apress.com/9781430243830 is Pro WF 4.5
"In Pro WF 4.5, you'll find the insight and direction for understanding how to build workflows using WF 4.5 and host them as long-running services using Microsoft’s Windows Server, for on-premises work, and Azure AppFabric, for hosting workflows in the cloud"
