This is a paper found through Science Blog -- see link here.
It is a paper in Evolutionary Ecology Research (March 2006), by Joshua Mitteldorf.
Chaotic Popluation dynamics and the evolution of ageing
Problem: "Genetic and demographic studies suggest that ageing is an adaptive genetic program, but population genetic analysis indicates that the benefit of ageing to the group is too slow and too diffuse to offset its individual cost."
Premise: "Demographic homeostasis is a major target of natural selection at the group level, with a strength that can compete with the imperative to higher individual reproductive value."
The author invokes a group selection type mechanism in enforcing the selective advantage of ageing. He uses computer simulation to show how this might work.
I'm not quite sure what to think of this. I'm afraid that I'm partly biased to dismiss it simply because it was published in a somewhat obscure journal. He claims among other things that current theories of aging are not well supported.
Here's a link to the Wikepedia entry on senescence. It goes through the evolutionary theories of aging and provides some links.