Remember when we told you all about the selling of the city's parks, and how that was the wave of the future? Well, it turns out the High Line Park, an example of a privately funded green space that is run by a nonprofit group, can't quite make the model work. After an overwhelming first few weeks (20,000 people per weekend day), the park's stewards are already pushing to create a "business improvement district" encompassing the area that has been positively affected by the park, and taxing that area to help cover the underestimated costs of maintaining it. [NYP]