I came across this, but am not sure how important it is:
From
http://launchd.macosforge.org/From a Technical Perspective:
This may appear like a bold statement, but we hope launchd will be as successful as virtual memory was. We view launchd as a manager of virtual processes. Much like virtual memory allows for a page of memory to be allocated long before it is backed by a physical page, launchd allows for processes to be allocated long before they’re backed by a concrete process the kernel knows about. The combinatorial advantages of this are huge, but we’ll get into those on another day, and with another blog post.
