Lights on high beam, two fingers on front brake, eyes darting side to side and at lest 4 cars ahead.... I lane split(technically called "lane sharing") all the time and have all my life in Calif.
Just a few yrs ago the CHP and DMV put out a notice how to do it safely, but in the last few months they have rescinded their recommendations, but have not outlawed it. http://www.latimes.com/business/auto...722-story.html

I heard they rescinded due to many SQUIDs going way to fast when lane splitting. It is not against the law to share a lane like when a cage at a stop while making a right turn and is way to the right in the lane and you see someone pull up next to them and is going to go straight that is okay. Where you can get in trouble with the law is doing it from the diamond lane which has a double yellow and you can not cross a double yellow line in Calif., but I see CHP motormen do it all the time, but don't try it I know from an issue I had with a CHP over it.
You can share a lane in any other lane on the freeway though. Because it is legal to split lanes you do not have to wait in the back of the line at a stoplight or stopsign and smell all them cages exhaust, you can ride to the front of the line.
A lot of cages will move over for ya if they see you and why I keep my high beams on when lane splitting, I try and give them a quick wave of recognition as I pass merry by...on my way.