Here's another reason why that glass of red wine may be good for you: scientists have identified a possible mechanism of action. Apparently, an ingredient in red wine, resveratrol, activates sirtuin, a protein that restores chromosomes to proper functioning. According to a recent story in the New York Times:

A new insight into the reason for aging has been gained by scientists trying to understand how resveratrol, a minor ingredient of red wine, improves the health and lifespan of laboratory mice. They believe that the integrity of chromosomes is compromised as people age, and that resveratrol works by activating a protein known as sirtuin that restores the chromosomes to health.

The finding, published online Wednesday in the journal Cell, is from a group led by David Sinclair of the Harvard Medical School. It is part of a growing effort by biologists to understand the sirtuins and other powerful agents that control the settings on the living cell’s metabolism, like its handling of fats and response to insulin.
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And, for additional amusement, ScienceDaily.com reports:

Researchers have uncovered what may be a universal cause of aging, one that applies to both single cell organisms such as yeast and multicellular organisms, including mammals. This is the first time that such an evolutionarily conserved aging mechanism has been identified between such diverse organisms.

The mechanism probably dates back more than one billion years. The study shows how DNA damage eventually leads to a breakdown in the cell's ability to properly regulate which genes are switched on and off in particular settings.
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These findings appear in the November 28 issue of the journal Cell.

For some time, scientists have know that a group of genes called sirtuins are involved in the aging process. These genes, when stimulated by either the red-wine chemical resveratrol or caloric restriction, appear to have a positive effect on both aging and health.

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The National Institutes for Health has this to say about it:

Scientists have found that the compound resveratrol slows age-related deterioration and functional decline of mice on a standard diet, but does not increase longevity when started at middle age. This study, conducted and supported in part by the National Institute on Aging (NIA), part of the National Institutes of Health, is a follow-up to 2006 findings that resveratrol improves health and longevity of overweight, aged mice. The report confirms previous results suggesting the compound, found naturally in foods like grapes and nuts, may mimic, in mice, some of the effects of dietary or calorie restriction, the most effective and reproducible way found to date to alleviate age-associated disease in mammals.

The findings, published July 3, 2008, in Cell Metabolism, may increase interest in resveratrol as a possible intervention for age-related declines, said NIA scientists. The authors emphasized, however, that their findings are based on research in mice, not in humans, and have no immediate and direct application to people, whose health is influenced by a variety of factors beyond those which may be represented in the animal models.

Resveratrol Found to Improve Health, But Not Longevity in Aging Mice on Standard Diet [nih.gov]