I guess that most people think big when they think of hedges, even though the ~1 foot tall clipped box (Buxus) hedges used as borders and in European knot gardens are equally hedges in my mind. Here's a nice photo that I found at Boxtrees Nursery (in England of course).
Maybe there's no smallish California native plant that lends itself to that style of hedge since the smallest pruned and maintained size among the plants that Joan recommends are the last two, which she says can be maintained at 6 feet tall and 4 feet wide. Or maybe with our high population density we're really talking about privacy and screening views when we in California talk about hedges. I looked briefly online for examples of California natives in a tightly sheared hedge, but didn't find any pictures. I do recall pruning a Lemonade Berry hedge with loppers and an electric clipper at a friend's house in Hope Ranch when I was a teen.
Scanning the archives of my (northern California based) listserve I came up with these suggestions for hedge plants:
Rhus integrifolia (the previously mentioned Lemonade Berry)
Galvesia speciosa (some selections will grow with a more compact habit than others)
Bacharris pilularis (Coyote Bush)
Garry elliptica 'Evie' or 'James Roof' or even the straight species
Rhamnus crocea can be used as a very formal hedge
Ribes viburnifolium (Evergreen Currant)
Cercocarpus betuloides (Mountain Mahogany)
Arctostaphylos 'Sunset' was recommended instead of McMinn as it was said to be more hedge-like and not require much in the way of pruning
Las Pilitas nursery, always a source of interesting information, has a section on hedges and screens. They include some more iconoclastic selections.
Finally, in a related blog post earlier, Naked behind a screen in the garden, KarenH suggested that I look at a Los Angeles area online native plant resource called Project SOUND, which I have mentioned very occasionally here. It's nice to see that it's up and running and thank you KarenH.