Our 4' passing law got voted out of committee and is on it's way to a house vote. http://www.pawalksandbikes.org/2011/05/safe-bicycle-passing-vote-is-coming/
4' is a lot. Given how ridiculous some people are about estimating where the edges of their vehicle are, I could see some people then trying to implement what amounts to a 10' law. In fact, was walking down the road in CT the other week, on the shoulder, when an oncoming SUV not only swerved to "avoid" me (I was 3' off a 4' shoulder), but swerved onto the opposite SHOULDER. I always wonder what those types would do with oncoming traffic.
I've got mixed ideas about passing laws. I'm only for them really because it provides one more thing to cite people who hit cyclists with, hopefully increasing the financial pain. If it weren't for that I have no idea where I'd stand.