From the lovely people behind mod_pubsub, have you seen BlogChatter?
It's a rather spiffy tool which shows blog updates in real-time. Discussion at Danny Ayers' site has sprung up about use of this tool when writing comments for blogs on especially hot topics. The idea is that, whilst writing your comment, a pop-up or inline frame could show whether somebody else has got your point in while you are typing it.
So in tune to their audience are they that Adam at mod_pubsub is now talking about it. Watch this space.