+1 - I've been using this daily for a while now and it really makes Twitter a much more connected experience. Seeing my friends pop up with those little green lights is great and being able to talk to them in real time is so much better than dealing with the PM lag.
Bonfire brings immediacy to Twitter... Like the previous commenter, the DM system has always felt a bit clunky and badly thought out - Bonfire sort of addresses that really well. Makes Twitter an even better real-time tool for collaboration...
Loving Bonfire - it's one of those "why didn't they think of that" things that fixes something that you didn't even realise was broken until someone shows you how it could work.