Few trains are as impossibly overcrowded as an L at rush hour. To ease the sardine-canning, the city will introduce a new ferry system. Starting in June, commuters in North Brooklyn, from Greenpoint to South Williamsburg, will be able to hop a city-operated water taxi to the Financial District or 34th Street (where a free shuttle bus will take them all points west.) Rides will cost anywhere from $3 to $5.50, far outpacing subway fares. But surely if you can afford to live in the luxury condos near the piers, you can afford a luxury commute, too?