reboot8 has its invitation to participate up. Unusually, no speakers are selected yet--the conference is being entirely decided by the attendees, with the organisers acting as facilitators to get people along, provide a minimum of structure, and keep the conversations and ideas flowing. reboot7 was my favourite conference last year. I did my scheduled Mind Hacks talk (on computer interfaces), then grabbed a room and held an ad hoc presentation/conversation on The 3 Steps: The History of Physics and the Future of Computing. There was something about the people and the energy of the conference that helped those concepts come together for me, and that last presentation has to be one of the most enjoyable ones I've done--the energy in the room was great, and I learned a lot from everyone who joined in.
Anyway, I'm not sure whether I'll be able to make it this year (be sure I'm going to try), but I highly recommend going along. Shape the conference on the wiki now, enjoy it later: reboot.