Clicking the post button throws your blogpost into the outer world. Is it finished ? No, quite often it's content need a little update. I find myself updating posts all the time. Because I give a person a wrong name. It was Robert Stoppels who built the aquariumpc exhibited on the CeBit. (post is updated). An error glitched into the sample code needs an update. And when reading back the text has become to abstract adding a screenshot highly clarifies matters.
The problem is that the original post has been collected by many a news agregator comming by. To see the update the reader has to revist your blog. I see no solution to that.