All it takes is critical mass, enough of us doing it that social mores, especially as regards workplace accomodations, change.
Over here in the frozen inbred tundra of Minnesota, in winter I used to see one, maybe two other tracks on the trail after a light snow. Now there are a dozen. And now, there are easily 10 bike commuters on the road where there were 2.
And in other cities, critical mass is starting to be acheived...on the road at least. The quantity of bike commuters in Paris was impressive, due I'm sure to a combination of 1.00/litre petrol and serious meausres taken to facilitate bike commuting.
Almost makes this particular observer look forward to 1.50/litre petrol. Fai de bèn a Bertrand, te lou rendra en cagant
Of course, since I only fill the tank once every six weeks or so I don't really care. I'd hate to be trying to commute by car however - not that I would: we live next to a train line.