This paper reports on the design, deployment and initial evaluation of "Wattsup", an innovative Facebook application which displays live data from a commercial off-the-shelf energy monitor. The Wattsup application was deployed and trialled in eight homes over an eighteen day period in two conditions - personal energy data viewable and friend's energy data viewable. A significant reduction in energy was observed in the socially enabled condition. The paper argues that socially-mediated discussion and competition made for a more enjoyable user experience.