For me, the hybrids are great if you want to make a statement AND you drive enough to get a return on the price through fuel savings. However, if you really want to save the planet, there are other options:
1) drive less and invest the premium you would pay for a hybrid into green tags. They provide carbon offsets at an efficient price
2) drive less, invest in green tags, and wait until plug-ins are available (and then buy). Most electric utilities let you select renewable energy as the source. Then you run your car mostly on solar energy. This not only saves the planet but also, if done by enough people, puts the US on a path away from becoming entangled in the geopolitics and militarization of oil supply.

I am selecting option #2.

Of course there are other options as well.