Now, admittedly, I can't ride bikes. I can run long distances, and my town has a sophisticated railway network which, although severely overcrowded, gets me from A to B in no time. If Velib is implemented in my city, however, there's a good chance I'm going to learn how to ride.
The basic concept of Velib is simple. There are several bike stations across the city, and you can rent bikes at one station and drop them off at any other station. This is much more efficient and convenient than systems where you must return your bike to the shop where you rented it. It was first implemented in Paris and has picked up quite a bit of traction in Europe, being now used in Copenhagen, Barcelona and many other major cities. A reasonable subscription fee is all it takes.
I feel that with our congested public transport systems, increasing car ownership ratios etc., encouraging biking ought to be the way to go, and this bike rental system is the best way to go about it. If your school or workplace is close enough, it can save you commuting costs, and if you use a polluting vehicle - such as a bus or, worse still, a car - you produce far less pollution. Ditto if you go by rail in a coal-burning city. Plus, cycling is a sport, and by encouraging it, you can potentially have a healthier population.