We are just starting to see a clear correlation between the price of oil and the fortunes of alternative energy stocks. Nowhere it would appear is this more marked than with solar and biofuel stocks. With oil prices now falling to a 6 month low this needs to be taken into account.

I think what this shows is a couple of points;

i) the price of oil trumps the price of carbon by a multiple (and will continue to do so) as a widely understood price signal for or against alternative energy investment - carbon markets because they are small and new, lack liquidity and long-term future pricing
ii) solar and biofuel stocks are starting to be looked at as sectors in their own right influenced by the global economy - rather than strange and exotic curiosities that behave uniquely as individual companies

Oil, like all prices never goes one way forever. For an excellent review of oil prices from 2004 - 2006, I recommend this wiki here.