Back in July I alerted readers to one of the more encouraging charts I have seen in some time, showing the dramatic transformation of American power generation away from coal and toward natural gas. It's not only a win for the environment, but a direct challenge to the idea that energy transformations are slow and therefore global dependence on fossil fuels will be difficult to reverse.
Here's something of a companion chart showing the rapidly declining cost of solar energy in the US. If this trend continues, natural gas may turn out to be merely a 'bridging' fuel between coal and solar:
Check out the full article in Scientific American, which argues that a version of Moore's Law (the processing power of computers doubles every two years) may apply to solar PV as well (although I note the article does not touch on the famed 'baseload' issue: how do you store solar power for when a surge is needed?).
Also, see this article in The Atlantic for what it might mean for climate change. The short version is that politicians should basically give up on carbon markets, since developing countries have no intention of cutting emissions anyway, and instead focus on technological solutions.