> This feels a lot like Google Docs's commenting system This was my first impression as well. The summary tree of replies to a thread seems like a possible imp

> This feels a lot like Google Docs's commenting system This was my first impression as well. The summary tree of replies to a thread seems like a possible improvement over Google Docs but the basic interaction workflow seems the same as Google Docs. Perhaps there is more innovation to be had by looking at the various specs for webpage annotation systems that have been proposed over the years?