A few people have been kind enough to ask, so I thought I'd post this. The MathsJam event I'm running in November (6 weeks to go!) has now closed early-bird registration. We have 54 full delegates, 4 day delegates, and 5 non-delegates. We have reached roughly half capacity already.
It looks like it will be easier to run the event than to give the money back ...
Clickable: http://www.mathsjam.com