Yes, you're correct. As of March 1, 2012 they will be required.
The state is adding Article 2.7, Section 4326 to Title 25 which will read;
ARTICLE 2.7. CARBON MONOXIDE ALARM SYSTEMS:
§ 4326. Requirements for Single and Multifamily Manufactured Homes of up to Two Dwelling Units. The requirements of section R315 of the California Code of Regulations, Title 24, Part 2.5, California Residential Code (CRC), herein incorporated by reference, shall apply to the design, construction and installation of approved carbon monoxide alarms in all of the following:
(1) New manufactured homes or multifamily manufactured homes with two (2) dwelling units manufactured on or after March 1, 2012, containing either a fuel-burning appliance(s) or designed for site-installation of an attached garage.
(2) Existing and used manufactured homes, mobilehomes or multifamily manufactured homes with two (2) dwelling units containing either a fuel-burning appliance(s), attached garage or designed for a site-installed attached garage, effective March 1, 2012.