If you registered during July 11 and July 27 and you also received an email that your registration was cancelled, you ran into a WikiSym / Google Checkout glitch that we just discovered. The cancellation is correct and you will have to register again using WikiSym 2012 Registration.
We believe that only a small number of registrations are affected. Still, it is annoying, and we apologize for any inconveniences this may cause!
Early registration has been extended until August 6.