This is one of those brilliant things like Cory Doctorow's writing that gives you REAL HOPE that the future will be a good and happy place, and that you might have a chance of making it to that point. Aubrey de Grey has been studying gerontology (the science of ageing) at Cambridge University and he proposes that with some science and engineering smarts, we can make huge progress toward extended lifetimes in the time left to even old farts like me (not quite 50 yet).
As I think about the benefits that I personally would like to get from nanotechnology, I think life extension is a big thing. Of course we'll have ever more powerful computers and capable robots and flying cars and all those nifty toys, and they'll all be very inexpensive, but I really want a lot more time to enjoy everything. And as my parents get older, I'd love to be able to offer that to them as well, though even by de Grey's very optimistic estimates, they're too old to benefit much.