In the lead-up to SummerOfCode, it is recommended that you contact potential project mentors about your project idea. Many of the projects on the SummerOfCodeIdeas page have a mentor listed; if they are listed in the form "gavin@" then add "@freebsd.org" to the end to give an email address. If there's no possible mentor listed and you do not know who would make a good potential mentor, please either email <freebsd-hackers AT FreeBSD DOT org> or ask in our IRC channel, #freebsd-soc on EFnet. As a last resort you can also email <soc-admins AT FreeBSD DOT org>, which is generally for administrative purposes but will assist special cases.
Once SummerOfCode commences, your first point of call should usually be your mentor. If your mentor knows in advance they will be unavailable for any length of time, he will assign somebody to act as a backup mentor for that time. Should your mentor become unresponsive or you wish to discuss something with the SummerOfCode administrators that you feel you cannot discuss with your mentor, you should contact <soc-admins AT FreeBSD DOT org>.