One of the items I'd like to see reasonably settled soon is whether longevity can be reliably engineered by targeting antioxidant compounds to the mitochondria and thereby slowing the accumulation of damaged mitochondria and their contribution to aging. We have good demonstrations that it can, and good demonstrations that it can't. Something interesting is clearly going on (as indicated by mice living significantly longer than they ordinarily would), but the details are still fuzzy. One of the lines of this research I've been following for a while is the work of Skulachev and colleagues in Russia, who seem to have developed an ingested compound called SkQ1 that can perform the mitochondrial targeting trick without the need for gene engineering of the sort employed by Rabinovitch. Here's the latest paper from that group: "Very low (nano- and subnanomolar) concentrations of 10-(6'-plastoquinonyl) decyltriphenylphosphonium (SkQ1) were found to prolong lifespan of [an] insect (Drosophila melanogaster) and a mammal (mouse). ... The lifespan increase is accompanied by rectangularization of the survival curves (an increase in survival is much larger at early than at late ages) and disappearance of typical traits of senescence or retardation of their development. Data summarized here and in the preceding papers of this series suggest that mitochondria-targeted antioxidant SkQ1 is competent in slowing down execution of an aging program responsible for development of age-related senescence."

Link: http://www.ncbi.nlm.nih.gov/pubmed/19120018