I'm personally not a big fan of traditional green politics, like passing laws that favor evaporative coolers over conventional A/C. (This happened in Denver recently) In most cases, market forces combined with lots of consumer education will produce the best results. "Unintended consequences" often result from poorly thought out laws (just ask Jared Polis). All other things being equal, fewer laws are better than more laws for many reasons. High on that list of reasons is the need for fewer lawyers.
Chris Nevitt, Denver's "greenest" city councilman, however, informed me of an interesting law passed by the city of Berkeley, CA. If you own a home and want to put photovoltaic solar on the roof, find a contractor and get a bid. The city will pay for it, then add the cost to your property tax bill to be paid over time.
With a financing scheme like that, there really aren't any barriers to PV ownership. The yearly savings on your electricity bill is instantly larger than the property tax increase.