Steve, webcosmo, I appreciate your offered suggestions, but they aren't what I'm looking for.
I asked about an automated way to deliver fine-grained change information. Writing a description of everything I've written after I write it does not fill the bill.
Actually, that approach puts an extra burden on the reader as well as on me. If she decides that she does want to look at the changes, she still has to find them. In the worst case they're scattered throughout the document, and she has to reread the whole thing -- or even compare it line by line to the previous version, which I'll have to take care to make available -- even though my blog or whatever describes the changes in general terms.
I'm dreaming of a tool that highlights changes on demand, something like Track Changes in Microsoft Word. That's not necessarily the only solution that would work, but it illustrates the type of solution that would work.