Ford and Azure have agreed to build Ford E-350 and E-450 hybrids by 2008. In case you're wondering E-350 and E-450 chassis-cabs are the basis for many Class C motorhomes. You might also see them in local use at the airports as small transports (i.e. getting you to and from the parking lot).
Source: News Desk - Ford E-Series Chassis Get Hybrid Conversions
The system, using a Ford 5.4-liter V-8 gasoline engine coupled with an electric motor-mounted inline with the stock drivetrain, is claimed to provide mileage improvements of up to 35 percent. Some of the gains are attributed to a regenerative braking system, which recovers a portion of the vehicle's energy while braking to recharge the batteries.