There are a significant number of Bike Fridays in my area (Morgan Hill, south of San Francisco Bay), although still a minority compared to conventional bikes. I Haven't seen too many Dahons. I had a 2003 Dahon Speedpro for awhile and liked it. I sold it and now I miss it so I've ordered a 2005 Helios SL.
Another point about coolness: kids got pretty excited about the Speedpro. I had one offer to trade me his BMX bike for it. His enthusiasm was dampened when I pointed out I wasn't sure the wheels could handle it if he bounced it up and down curbs.
I too would love to see folders catch on as utilitarian bikes.