Quite a bit, according to a recent National Technology Readiness Survey. As FutureWire puts it:
If all workers in the US who are able to telecommute actually worked from home an average of 1.6 days per week, the gasoline savings would total $3.9 billion (not to mention reduced car emissions, less stress and more productive time).The FutureWire post goes on to suggest that, in light of this fact, there should be a national initiative to encourage telecommuting. I like that idea. Another reason that businesses should be thoroughly prepared for telecommuting is the possibility of an avian flu epidemic, as eWeek discussed a few months ago.