Whatever one thinks about the so-called "rebound effect" or the role of efficiency in contributing to emissions reductions goals, the Breakthrough Institute (where I am a Senior Fellow) has done a great service to the discussion by publishing a new literature review on the subject. You can find the review here in PDF and a PowerPoint overview here in PPT. They discuss the new report on their blog here. This massive effort represents think tanks at their very best, and is likely to be the definitive literature review for years to come. Whatever your views or level of expertise, if you want to dive into the subject, I can think of no better place to start.