This in today, from an article in the Yahoo Health blog entitled The Most Dangerous Thing You'll Do All Day:
Scientists at the Pennington Biomedical Research Center in Louisiana analyzed the lifestyles of more than 17,000 men and women over about 13 years, and found that people who sit for most of the day are 54 percent more likely to die of heart attacks.
What makes this particularly interesting is that sitting appears to be a causal factor for heart attacks regardless of any other lifestyle considerations, i.e. it doesn't matter how much a person otherwise exercises or how fit they may otherwise be. Other factors such as diet and whether you smoke or not were also irrelevant. If you sit for much of the day, it is a factor.
For a long time, I have thought about the possibility of incorporating a standing desk into my work routine, mostly because of the negative impact of sitting for long periods on posture and back health. Looks like there's another good reason to start checking out some standing desks.
If you don't know what they are, just google "standing desk" to find lots of resources about them. You can also find one person's informative account of her experience switching to a standing desk here.