The way this thread turned out in response to Descan's post makes me very happy. For some reason, most people are naturally resistant to the idea that not dying is awesome. Then again, Bay12 is most definitely not most people.
Aaaaalso, it's not as simple as just telomeres. And if anything, yes, plants have identical biochemistry to animals except for the whole photosynthesis thing. The differences start higher up. Telomeres are a part of the answer - they demonstrably shorten with age, their removal provably causes many symptoms of old age and once the mice who had their telomeres removed, once they were given telomerase (an enzyme that lengthens telomeres, humans produce negligible amounts of it), effectively de-aged.
There's another thing, namely that most types of cancer rely on the gene that encodes telomerase production (hTERT gene) activation, otherwise the cancer cells would start dying out after a number of divisions - but that means if we would activate hTERT in humans, we risk helping out cancer by taking care of one of the key mutations, or maybe the lengthened telomeres would take care of that. Who knows.
But, it has also been proved that some parts of the damage associated with the symptoms of old age is unrelated to telomerase - for example, there are also mitochondria, which suffer from accumulation of byproducts (AGEs, the acronym is completely accidental), responsible for example for diabetes, and DNA damage - because mitochondria have their own set of DNA (which doesn't have telomeres, because it is circular like bacterial DNA).
Sooooo, there's still some work to be done.