I've never done any cyclocross events and don't own a cyclocross specific bike but I will probably be doing the Sept 19th event up by OC with my brother if anyone has any interest:
http://www.socalcross.com/schedule.php
I think it'll be a lot of fun. Short, no pressure, good crowds. I think they'll have a kids race, too, that I can put my kids in. At the end there will be a relay race to raise cash for my brother's non profit.
We have an extra medium sized mt bike here that someone could maybe borrow...or somone could maybe borrow my mtb if they aren't in the same heat.
There are also some s.d. events coming up...