I climb with a guy from Britian and he is 71 - still doing nice rock routes and leading hard ice in Canmore. I did the Wapta Traverse with a guy who was 71 and he kicked all our butts.
Also in France last year the guys in the 80's were easily doing 5.8+ on various rock routes, I even got some pointers from them. I had heard about another guy who was 83 and had just died in an avalanche doing an extremely hard route on one of the mountains of Cham.