In the discussion on metafilter regarding the Brown Equals Terrorist, someone posted a nice link to a summary of the rights of photographers.
It’s not clear that this document is up to date with respect to the recent Supreme Court decision in Hiibel v. Nevada.
In trying to determine what the actual rule of law is here in California, I found this newspaper article, which definitely sends a mixed message. My reading of the Hiibel case is that police are not allowed to stop or detain you for purely arbitrary reasons, but Hiibel does grant them wide latitude in asking for identification if they suspect a crime has been committed.
It seems to me that given the findings in Hiibel v. Nevada, refusal to identify could be prosecuted under California Penal Code 148, the relevent section presented below.
148. (a) (1) Every person who willfully resists, delays, or obstructs any public officer, peace officer, or an emergency medical technician, as defined in Division 2.5 (commencing with Section 1797) of the Health and Safety Code, in the discharge or attempt to discharge any duty of his or her office or employment, when no other punishment is prescribed, shall be punished by a fine not exceeding one thousand dollars ($1,000), or by imprisonment in a county jail not to exceed one year, or by both that fine and imprisonment.
Ironically, this section largely deals with penalties which seem arise from intentional jamming of police radio frequencies and offenses related to someone grabbing a firearm from a police officer. The penalties involved are up to $1000 in fines and a year in prison. It would seem to me that applying this law to simple refusals to identify is a broad expansion of its original intent. Indeed, the Herald article above seems to indicate that the district attorney refuses to prosecute such cases where the suspects are not held on other charges: a sane and sober interpretation that helps to protect the people against overly zealous police officers.