On Don's recommendation, I picked up Essential WF. In the forward, Don writes "[S]omething big is about to happen." I'm only part way thru chapter one, and this is already a must read. Go get it. Now.
In the preface, they define the term "Reactive Program", which I'm adding to my personal lexicon.
"Windows Workflow Foundation (WF) is a general-purpose programming framework for creating reactive programs that act in response to stimulus from external entities. The basic characteristic of reactive programs is that they pause during their execution, for unknown amounts of time, awaiting input."
That "unknown amounts of time" is the kicker. Here's a paragraph from early in chapter one that expands on that:
"Real-world processes take a long time - days, weeks, or even months. It is wishful thinking to assume that the operating system process (or CLR application domain) in which the program begins execution will survive for the required duration."
Gee, that sounds familiar doesn't it?