I received an email today from a Ron Paul Meetup Group stating that Ron Paul can be written-in in California. I cannot verify the validity of this. Maybe someone else can.
Here is the email I received:
“The California SOS certified Ron Paul today as a write-in candidate. Attached is the official letter from the SOS. You may write him in knowing your vote will be counted.”
Here is the PDF about Ron Paul’s Write-in Status in CA