This research has been doing the rounds:

This week researchers from the Dana-Farber Cancer Institute reported that the length of telomeres - which shorten with age - determines virtually every aspect of aging from wrinkles and gray hair to the onset of dementia, diabetes, and heart disease. At least that was the case in the mice they studied in a report published in Nature.

"We think we've identified the core pathway that really helps explain many different theories of aging," says study co-author Dr. Ronald DePinho, a geneticist at Dana-Farber. "Our study provides a unified field theory for aging."

In a nutshell, once telomeres shorten to a particular length, aging accelerates. Shortened telomeres allow the cell's DNA to become damaged, which activates a gene, p53. This sets off a warning to shut down the cells' normal growth and division cycle until the damage can be fixed or, if not, the cells die. At the same time, cells with short telomeres have power plants, or mitochondria, that are no longer operating at full capacity. This leads to malfunction in crucial organs like the brain, heart, liver, and pancreas, as well as a loss of muscle, and eventually extreme weakness and frailty.

(The paper is at Nature if you're the sort who likes to read primary sources). That's an ambitious declaration from the researcher quoted above - I can only imagine it's taken somewhat out of context and then hyped up by the science writer for the introductory paragraph, as it is certainly the case that damaged mitochondria and shortening telomeres are only two of the possible reasons we suffer age-related degeneration. Many of the other causes of aging involve a build up of varying forms of damaging waste product that the body cannot remove - mechanisms which are quite capable of causing disability and death on their own, telomere shortening or no telomere shortening.

That said, telomeres, mitochondria, and p53 are all large and healthy areas of research when it comes to the biology of aging. I imagine that anyone would be pleased to produce good evidence that might mechanically tie them all together, such that one or more are secondary effects rather than primary causes. From an economic perspective, we should all be hoping that some of our present candidates for the primary causes of aging turn out to be secondary effects - because then we don't have to devote any time towards developing repair biotechnologies to fix them.

On a closer reading of the new research, I have to say that it looks to me very much like an independent confirmation of discoveries from 2007 and 2008 relating to mitochondrial damage, telomere length, and the enzyme telomerase. In a nutshell, it may be that telomere shortening is entirely driven by mitochondrial dysfunction:

Researchers have put forward evidence to suggest that telomere shortening is caused by accumulated damage to mitochondrial DNA - essentially collapsing two areas of intense interest for gerontologists down to one root cause, if confirmed. ... [It may be the case that] poorly functioning mitochondria lead to telomere shortening, and telomerase somehow improves mitochondrial function to prevent that shortening. This is in place of the more expected path of undoing ongoing telomere shortening by adding extra repeat sequences to the end of the telomeres - that being the better understood function of telomerase.

I don't immediately see anything in the Nature paper that would rule out this interpretation of the link between these two fundamental mechanisms of aging. Like the earlier researchers, this present group also found that boosting telomerase activity improved mitochondrial function, though I believe they are arguing that the improved function happens as a secondary result of interactions between telomere length and p53. There's certainly plenty of room amidst the uncertainty for contradictory interpretations at this stage.