I've noticed an increase in bike commuters, too. Some obviously haven't thought it through, like the guy a couple of weeks ago in nice slacks, a tie, and a light blue shirt....which was soaked from collar to belt in sweat. Glad I don't share an office with that dude.
The sad thing is, I bet a lot of those commuters that "went off half-cocked" gave it up after the first time or two, when all that was wrong was their preparation and technique.
I'll tell you what I've seen the biggest increase in: Scooters! I really don't understand it, though, as in my state once the engine is 50cc or larger the rider has to have a motorcycle endorsement on his operator's license. If I were to want to go that way, and had to go through all the trouble to get the MC endorsement, I'd just buy a small motorcycle and get the handling advantage of the bigger diameter tires.