Fuel Cells have been around for quite some time now, they were for example used in the US Space Program as the batteries of that time were too heavy. There have been quite a few good examples of the adoption of a fuel cell in the drive train of a hybrid vehicle, but so far the big car manufacturers are still testing and adjusting their prognosed dates. For now the date they will launch a fuel cell hybrid is set around 2012 (or after that ofcourse).
Without going into the discussion wether a fuel cell powered vehicle is 'better' than a pure electric vehicle, I think the main reason for the car manufacturers to go into the fuel cells would be that it is harder to obtain and own battery technology. Fuel Cells are around, but the companies producing them are still relatively small making it expertise that is cheaper to purchase.
We'll just wait and see when the Fuel Cell car rolls out of the factory, in the meantime check out what Volvo, Mercedes and BMW for example are doing with their Fuel Cell programs: