Solar Boats - up to 60 passengers and 11 knots in Europe; NYC ferry service suspended
The Swiss Firm MW Line makes solar boats that are ferrying people around lakes and rivers in Switzerland, France, Italy, and the United Kingdom. The only backup power, apparently, is on-shore charging from the grid. They’re also the shipbuilder for the PlanetSolar project which plans to have a solar-only craft in the water ready for a two-person, 120-day around-the-world trip in 2009. 
And here’s a gallery of the boats they’ve been producing:
The New York Times reported today that New York Water Taxi, the only operator of Queens/Manhattan and Brooklyn/Manhattan ferry service has cancelled service for the winter - largely because of fuel price increases. A ferry powered by photovoltaic cells wouldn’t be directly affected, if at all, by petroleum price increases.

