Garret from HipChat here - We obviously agree that lots of apps have used chat bubbles in logos over the years. In fact, probably way too many. The only reason its an issue this time around is that our users are genuinely confused when they try to use both apps. This didn't happen when they used iChat, Echofon, or any other bubble-logoed apps alongside HipChat. The new Messages icon is similar enough that it's a problem, and we don't want our users to be confused.