One of my recurring themes is the challenges that California law imposes on employers. (I had a great idea for an image to put here, but it's incredibly difficult to find a tasteful photo of someone beating a dead horse.) We've summarized the various legal requirements in these guides.
But San Francisco employers have it worse. In addition to the rigorous and constantly shifting state law requirements, they also have to deal with onerous city requirements (including the second highest minimum wage in the country). There are also requirements for commuter benefits, per-employee spending on health care, a paid sick leave ordinance, and more.
My colleague Tyreen Torner prepared an excellent summary of these requirements that you can find here. If you have employees in San Francisco, I'm sure you'll find it useful. If not, don't throw it in the trash. Along with everything else, San Francisco has the toughest mandatory composting and recycling law in the U.S.
Updated April 2, 2012 to reflect that Santa Fe, NM has edged us out for highest minimum wage by a nickel.