According to an article in today's New York Times , it's a growing trend.

"While the sharing of rooms was once largely limited to academia and nonprofit groups on a shoestring budget, Bjorn Hanson, an analyst for PricewaterhouseCoopers' hospitality division, said the idea had begun to spread through corporate America. "Just in the last year, we've been hearing about a number of companies that are requiring employees to share rooms on trips," he said."