I would be shocked if the little experiment in Chicago succeeds. With only 100 bikes and only a handful of stations, all in touristic areas, I have to wonder who would use this system. With no stations in residential areas or at El stops, it is useless for commuting. Most tourists would probably be a little too terrified of our downtown traffic to take these bikes anywhere but along the lakefront - where we already have rental bikes. What I fear is that this system won't be used, and politicians and city planners who don't support biking will be able to point to this failure as evidence that there is no demand for a bike sharing system in Chicago.
I have seen a system that really works, BIXI, in Montreal. They have about 250 stations with something like 5000 bikes in all. Most Metro stations have BIXI stations, too. You can literally go anywhere in the city by BIXI. I'm sure that tourists use the system (I did), but most of the people you see riding the bikes (and you see a LOT of them - in two years they've had over a million rides) look like locals - business people and students.
In order to have a chance of success, I think a bike sharing system in Chicago has to be directed more toward people who are already open to cycling in the city - e.g., younger commuters and students in neighborhoods where decent cycling infrastructure (bike lanes and quiet streets) already exist. Stations at CTA red line stops, and at DePaul and Loyola, along with a few in the Loop, might be enough to form the core of a system that could grow to encompass most of the city.