Tim, this is really insightful work! One addition: it’s curious that powerusers (ie those using Tweetdeck, and, I presume, those using other third-party clients) don’t see hashflags. This is doubly curious in Tweetdeck since Twitter recently stopped supporting the standalone clients and essentially forced everyone to use the web-based version. If that move isn’t, in part at least, to synchronise the experience, I don’t know why they would have bothered. So, are hashtags trying to push everyone into using the main Twitter client, or is it too hard to get hashflags to appear anywhere else, do you think?