Carpobrotus Edulis is the name of this plant. It is also known as Iceplant, Hottentot Fig, or Fig-Marigold. According to this website, it thrives on neglect! That is, it doesn't require much water, basically just sunlight. Hottentot Fig are beautiful and are found throughout the bay area, though they are not native to California. According to UC Davis' site, they are African plants that were brought to California in the early twentieth century.
I first noticed these plants when I visited San Francisco prior to moving here. Actually, my dog seemed to take a special interest in them first and they then caught my fancy as well.
In my obsessive quest to find out what these plants are called, I discovered some interesting botany websites. One of them is http://www.ubcbotanicalgarden.org/, where you can actually post questions regarding plants, etc. in their forum. The curators at UC Berkeley's Botanical Garden were also an extremely helpful resource in researching this plant's origins.