My attention was drawn, via John Hawks, to a review of Ray Kurzweil's Fantastic Voyage by aging researcher Tom Kirkwood that is available - for paying subscribers only, sadly - at Nature. To get an idea of Kirkwood's background and thoughts on the matter of healthy life extension, you might want to read one of his recent EMBO Reports papers. John Hawks, who is more the Nature subscriber than I, notes:

The review is basically supportive of the actual content of the books, but at the same time critical of the hype.

...

We know, for example, that, in model organisms, boosting some of the mechanisms for cellular maintenance and repair can indeed extend life-span. This does not mean that the same techniques will necessarily work in humans, because we know from comparative studies that humans are already endowed, for good evolutionary reasons, with much better maintenance systems than shorter-lived species. By analogy, a design modification that boosts the performance of my own modest car will not necessarily make a Maserati go faster, as the Maserati is engineered for peak performance already. But we can try.

I don't think that the current brace of funded work looking at manipulating our metabolic biochemistry for enhanced health and longevity - largely spreading out from research into the mechanisms of calorie restriction - is a bad thing. But it is a different and most likely less fruitful field of science than any form of directly tackling repair and prevention of age-related damage. It's tuning the engine rather than coming up with a better design for longer-lasting components or better tools for repair.