From this I take it that a CA ebike is exempt from any license or registration requirements as well as the DOT helmet requirement.
V C Section 24016 Motorized Bicycle Electric Motor Safety and Equipment Requirements
Motorized Bicycle Electric Motor: Safety and Equipment Requirements
24016. (a) A motorized bicycle described in subdivision (b) of Section 406 shall meet the following criteria:
(1) Comply with the equipment and manufacturing requirements for bicycles adopted by the Consumer Product Safety Commission (16 C.F.R. 1512.1, et seq.) or the requirements adopted by the National Highway Traffic Safety Administration (49 C.F.R. 571.1, et seq.) in accordance with the National Traffic and Motor Vehicle Safety Act of 1966 (15 U.S.C. Sec. 1381, et seq.) for motor driven cycles.
(2) Operate in a manner so that the electric motor is disengaged or ceases to function when the brakes are applied, or operate in a manner such that the motor is engaged through a switch or mechanism that, when released, will cause the electric motor to disengage or cease to function.
(b) All of the following apply to a motorized bicycle described in subdivision (b) of Section 406:
No person shall operate a motorized bicycle unless the person is wearing a properly fitted and fastened bicycle helmet that meets the standards described in Section 21212.
(2) A person operating a motorized bicycle is subject to Sections 21200 and 21200.5.
(3) A person operating a motorized bicycle is not subject to the provisions of this code relating to financial responsibility, driver's licenses, registration, and license plate requirements, and a motorized bicycle is not a motor vehicle.
(4) A motorized bicycle shall only be operated by a person 16 years of age or older.
(5) Every manufacturer of a motorized bicycle shall certify that it complies with the equipment and manufacturing requirements for bicycles adopted by the Consumer Product Safety Commission (16 C.F.R. 1512.1, et seq.).
No person shall tamper with or modify a motorized bicycle described in subdivision (b) of Section 406 so as to increase the speed capability of the bicycle.
Added Sec. 3, Ch. 804, Stats. 1995. Effective January 1, 1996.
Source -
http://www.dmv.ca.gov/pubs/vctop/d12/vc24016.htm
Yeah, ebikes rock!