I've noticed that Martin Fowler's '[bliki](http://www.martinfowler.com/bliki/)' accomplishes this. He publishes a post in one or two paragraphs, and then updates them over the subsequent days. And in my RSS reader it shows up as a new post every time he makes an update, but points to the same page - albeit to a new section therein, so you can start reading from where you left off.