I'm not sure how big of a role employers play. I think for most people the number one thing that keeps them from bike commuting is safety. They look at the routes between home and work and don't want to even think about riding a bike on them. Beyond that though, is the image of spandex clad cyclists an issue? Do people have bikes that are appropriate for commuting? Would it be easier to get people to start riding a mile or two to dinner or for ice cream or groceries?