I heard about this on NPR today. Gliese581 isn't too far away in galactic terms (about 20 LY)...
http://arstechnica.com/science/news/2011/05/new-climate-model-suggests-exoplanet-may-support-liquid-water.arsAt least it's close enough that we should be able to learn a lot more about it in the coming decades, as better telescopes/detectors come online.