The driving force behind providing a telework policy is different for the employer and employee. Employers move to telework policies because it saves tens of thousands of dollars every year and employees embrace teleworking because it provides a greater work-life balance. It's a win-win for both parties.
I would say that 99 percent of the companies out there would benefit on both productivity and collaboration by offering some forms of work flexibility to their team -- whether it's as minimal as having a flexible schedule once a week or telecommuting a half-day a month, to more comprehensive flexibility options.
I'm not saying it's easy, and I know that Marissa Mayer has her work cut out for her. But for a technology company like Yahoo! to say that telecommuting cannot be host to healthy, productive work environments in any way -- compared to the "hallway and cafeteria discussions" -- it's just plain hypocritical.