A good discussion is underway in the Immortality Insitute forums on the topic of the recent klotho research. Michael Rae suggests that this was yet another experiment in which life span was not measured against the proper control groups - something that has bedeviled much research in mice in the past, and that calorie restriction groups have spent a fair amount of time and energy discussing.
All that the extra klotho dose did was move the 2 transgenics closer to - and in no case fully! - the average and maximum lifespan expected of mice that aren't genetically disfavored or in poor husbandry conditions. In the case of the females, the effect is nearly negligible; since the data were never formally reported, I'm guessing that the difference was statistically nonsignificant, as I suggest it was also "clinically" and scientifically.
Of course, a zillion things - melatonin, cysteine, hydroxylamine, alpha-tocopherol, ethoxyquin, 2-mercaptoethylamine, etc etc - do this. This tells us something about how antioxidants can counter the abuse of poor animal husbandry or bad genes, but it doesn't tell us anything about basically healthy animals - and even less about aging per se.
Michael goes on to make a point I agree with wholeheartedly:
What is needed is interventions which directly target aging damage.
Klotho is not that, even if the experimental conclusions are validated - slowing aging via metabolic tweaks is not the way to radical life extension.