From the Life Extension Foundation News: "Aubrey de Grey reckons 'we have a 50-50 chance of developing a human rejuvenation therapy that works.' His timetable calls for 10 years to prove the scheme works for mice, and another five years to apply the techniques to humans. From then on, 'radical life extension' will mean 'the indefinite postponement of aging.'" On the other side of the coin: "Olshansky believes it is misguided to regard aging as a 'disease' that can be 'fixed.' Instead, he sees it as the inevitable result of irreparable cellular damage that is a byproduct of living." Olshansky's views are widely regarded as indefensible - some cellular damage can already be repaired, and the research required to repair the rest is not a mystery.
Link: http://www.lef.org/news/LefDailyNews.htm?NewsID=1259&Section=AGING