For a while there was a rumor floating around that you needed to notify the CA DOJ of any change of address to comply with BS23 and RR89. I received a call from the DOJ today and they stated there is no such requirement. However, the man suggested it may be a good thing to do just so the address on your SUR registration matches your DL. I'm inclined not to notify the DOJ (since the regs are tied to your DL, it probably doesn't matter as they will find you! he he), but if you are so inclined, the man said the way to do it is to make a copy of your original registration form, write the new address on the copy, and mail it to the PO BOX listed on the registration form. You should attach a note stating what it's about as well.
He stated the only reason you may want to notify the DOJ is so they can get you a new original with the new address. That way, if a LEO ever asks to see your regs, the address matches your DL.
Personally, I think they just want to keep their database current, but again, it is not required.