There is a mini meme in CMS-land that says "CMSs don't need wokflow engines because most publishing workflows are 4-eyes" (see Janus Boye's and Deane Barker's posts). I believe that the underlying assumption of this claim is that the term "workflow"
- denotes steps performed by humans and
- applies mainly to publishing.
In my opinion this definition is too narrow - a workflow should be considered a series of steps performed either by a human or automatically. Here are some actual use cases of CQ's workflow engine that I have seen. Some involved manual steps, whereas others did not:
- e-mail notifications to authors when articles get published
- automated spam check for incoming reader comments
- automated Twitter posts when a blog post when online
- thumbnail generation of imported images
Therefore, I prefer to think of CMS-workflow engines as content automation engines.
One important aspect of that is the "automation" can also imply manual steps - so simply the ability to run some code inside of the context of the CMS is not enough for a workflow engine. In real-world scenrios you additionally need a user interface for manual steps.