A cheaper way to start bike sharing?

Bike sharing programs, which offer people an alternative to driving and helps fill the gaps in transit networks, have been increasing in popularity in Europe and are now catching on in the US with programs such as Denver's B-cycle and Nice Ride in Minneapolis.  SoBi--short for Social Bicycles--is attempting to build the bike share momentum by cutting capital costs for modern bike sharing.  
While European and, now, North American bike-sharing typically use specially designed, proprietary bicycles, the SoBi design incorporates a GPS system and a locking mechanism in a compact box/rear rack that can be attached to any bicycle, also allowing members to lock the bike up at any bike rack.  The design is being touted as a way to significantly cut the capital costs of starting a bike sharing program.  SoBi is entered in Pepsi's Refresh Project for a chance to test drive the program in NYC.