In order to satisfy a 2008 state law that requires reduction of greenhouse emissions to 1990 levels by 2035, the Metropolitan Transportation Commission and the Association of Bay Area Governments have approved a strategy that would steer growth into already developed areas around transit hubs. Although the cities and counties are not obligated to follow this strategy, the money for transportation improvements would go to areas that adhere to it. The strategy will undergo further analysis before it is considered for approval in spring.
The critics argue that the strategy is unconstitutional and would deprive people of their rights to live in single family homes outside dense urban areas. The supporters believe that it would protect open space and encourage development closer to jobs and transit lines.
Here is a brief video on San Francisco's Proposed TransBay Terminal
Reference: After a lull, San Francisco’s set to increase housing construction.
Cabanatuan, Michael, Land-use plan calls for new growth near transit, May 19, 2012