I posted about it before, but Simon ‘corecode’ Schubert supplied more details: there’s going to be a DragonFly hackathon at the 23rd Chaos Communication Congress in Berlin at the end of the year. Visit the IRC channel #dragonflybsd on EFNet if you’d like to coordinate rooms/board/meeting up.
This could be quite good; the recent NetBSD hackathon generated a lot of results.