Dave,
It's interesting that you mention dotLRN because I was thinking about the way dotLRN works when I decided that being able to replace acs-subsite might be a good idea. It occured to me that a lot of the glue that dotLRN provides to the other packages could be the kind of thing that subsite replacement packages should be providing. I've no idea what the common elements are right now but it seems like there should be some kind of standard contract there...
