It seems that newsfeed items on the user profile pages (e.g. https://secure.phabricator.com/p/joshuaspence/) do not get updated.
For example, if I close a diff that was authored by user X and leave a comment "foo", then "@joshuaspence closed revision D123" will appear on the newsfeed of user X's profile with the comment "foo". If I then edit my commit on D123 to "bar", then the newsfeed text does not change.