Although folding and other portable bikes are commonplace in many areas, many are not full-sized when deployed. Bike manufacturer Cannondale is throwing their expertise at the idea of a folder and have developed the "On," a full-sized folder that incorporates some smart design and weight-saving techniques to make a bike that is both durable and light. (In theory!)
A 2004 "Jacknife" prototype, developed in partnership with the Elisava Design School in Barcelona, had a hydraulic pedaling system that ditched the chain entirely. The On has a chain, but one encased fully inside a single-sided "fork" that can be fully detached from the rear wheel without loosening the gears or disk brakes.
For now Cannondale just has the prototypes, which I imagine they'll be shopping around to retailers and customers to see what the interest level might be. Even if they don't release a commercial version, it's quite a piece of engineering.