After googling around, I've come to the conclusion that this is a succulent plant called Aeonium - a drought-tolerant plant perfect for the climes of Southern California. It forms a large rosette (as big as my head!) of pink-rimmed leaves.
~ The Arlington Garden in Pasadena. This Mediterranean-style 'water-wise' garden is built on a lot that once boasted a million dollar home at the turn of the last century.