Extramarital affairs are in! At least according to Noel Biderman, who has attracted 8.5 million people to his Internet dating site devoted to married people seeking affairs since he founded it in 2002. A profile of the AshleyMadison.com founder in today's Bloomberg BusinessWeek suggests cheating is as popular as ever, especially with internet forums making it easier to meet people. "The Internet dating market is worth $1 billion to $1.5 billion in the U.S., according to industry website Online Dating Insider, and some portion of that, from 10 percent to 30 percent, depending on whom you ask, involves people who are already in relationships," writes Sheelah Kolhatkar. And based on the $20 million profit Biderman's company is expected to generate this year from Ashley Madison's 1.3 million paying customers (creating a profile is free but initiating conversation with someone will cost you up from $49), the man might be onto something.

But are that many married people really searching for someone else? A recent study by the University of Virginia suggests the market for unfaithful spouses may be shrinking, not growing. UVA Sociologist Bradford Wilcox is the director of the Marriage and Family Project that conducted the study, and told Providence Journal contributor Rita Watson that "22 percent of ever-married men and 14 percent of ever-married women said they had had an extramarital affair over their lifetimes. Also infidelity overall has not increased over the last 20 years."

Perhaps our keen observation of the lives of celebrities has given us a skewed perception of just how common adultery really is. Wilson insists that "infidelity in sports and Tinseltown is higher than in the general population, where rigorous research reveals that only a fairly small minority of married people are unfaithful over a lifetime." And observing the latest box office hits, Splice Today's Collin David suggests that movies, such as the recent No Strings Attached, Hall Pass, and The Dilemma, also perpetuate this notion that infidelity is not only popular, but hilarious.

So how often do people cheat? The real answer to that question is unclear. The number of people who can resist the urge may be on the rise, but in the mean time, Biderman and Co. are banking off those who can't. Except, as Oxford research fellow Will Davies pointed out back in October, that may be counterproductive: once you make infidelity the new normal, doesn't it lose a bit of its appeal?