Hong Liu, Yanzhen Fan, and Hongqiang Hu of Oregon State University have authored an article claiming to have achieved 1,500 watts of electricity from a 1 cubic meter microbial fuel cell reports ScienceDaily.  These fuel cells use bacteria to break down waste water pollutants and generate electricity and clean water in the process.  This is about 10 times the power of previous air cathode microbial fuel cells.  About 5% of electricity generated in the US is used by water and waste water treatment plants so this could be a significant development if it can be scaled up.  The current thought is that smaller systems for use by individual houses will be ready for use sooner.