The WashCycle Blog is reporting encouraging numbers for DC's Smart Bike Program despite it's limited scope with nearly 1000 subscribers and 150 users per day.
An earlier WashCycle post discussed the inconvenience of carrying a helmet around to use the for bike sharing and pointed toward the availability of folding helmets. The StashKit folding helmet seems to be currently available for sale online through European retailers (I found only one) and sells for about $85 at the current exchange rate.
Perhaps a barrier for sale in the US may be a lack of CPSC certification of the helmets, Treehugger blog reports that the helmet has "Europe's CE certification but seems to lack the safety credentials for sale in the USA". That doesn't necessarily mean that this helmet is less functional than US brands . Making bike helmets portable is one step towards improving helmet compliance.