Hacker News Reader

didn't adobe do this? i can't remember what it was called though.. but it was similar - set up in browser editable areas on existing html

Are you talking about Contribute?

found it - was "inContext" which seems to have been scrapped, or at least bundled into something else. http://incontextediting.adobe.com/

which shows the problem of managing something like this through a third party anyway!