We need Water! >> desalination - current situation and future prospects
I find it interesting to monitor technologies like these because the biggest challenge of our generation will be the question of how to sustain our current way of life, given the declining availability of resources (oil, water, etc.) on the one hand, and growing demand for these resources on the other.
Besides the question of how to secure access to much needed resources, there's the question of how to counteract the effects of using those resources (global warming, etc.). It's nice that we have the Kyoto Protocol, but we'll probably need a hell of a lot more to counter the effects of global warming and soforth.