Oh yeah, "Dude" is quintessential California-speak. It's something you call people, and it's also an expression on it's own (e.g. something good happens and everyone says "Dude!"). My wife (native Californian) says "Dude" constantly, and calls me "Dude", too -- it's pretty funny.
>>(e.g. something good happens and everyone says "Dude!").
One of my friends is from Vietnam originally but since immigrating here has been in the Bay Area exclusively. He uses "Dude" all the time
"I was like--Dude! Can you follow me any closer on the Freeway?"