well you probably don't know but automattic guys (all, girls too:) ) are interesting, we all probably know there is autosave feature in worpress.com blogs well to find something new and interesting try doing this now whenever you see a comparison table downside the post, page in wp-admin section
'There is an autosave of this page that is more recent than the version below. View the autosave'
try doing it,
comparing same versions of the autosave
and see what follows