Olympic Powder Coating is in Santa Ana, FYI.
I'm taking an old Schwinn to Palms Cycle in West L.A., they do powdercoating, and they tell me they can disassemble the bike for me and put the vintage Schwinn decals over the powdercoat. Wow. Being a C&V guy, that's my choice. (Their website says they do painting, but when you go in and ask, they really do powdercoating. Who knows, maybe they do painting also. They also do restorations of classic & vintage bikes.)
I've heard good things about Central Powder Coating (Brea) and Five Star Powder Coating (Redlands).
If you want actual painting, most of the really cool folks are in San Diego, but you might try Lizart in Lakeview Terrace - mostly custom paint jobs, (818) 896-1749. Down south, you have Joe Bell, Wanta Frames, and Cyclart, which do either new custom paint or restoration paint.