A nice piece by Jake Mooney in the City Section called, 400 Umbrellas Spell Park Slope:

The program has a certain “only in Park Slope” feel to it. The
neighborhood is, of course, home to a thriving food co-op where all
10,000 or so members have to work monthly shifts, and Catherine Bohne,
the umbrella program’s organizer and owner of the Community Bookstore,
says residents are always helping each other out. Once, she said, she
found a bag of dog food on the sidewalk with a sign that read,
“Perfectly good food, only my dog just doesn’t like.”

Not that
the umbrellas are solely a charitable endeavor. Although they are
partly a promotional campaign, one that has drawn a swarm of reporters
bearing free publicity, the social experiment is what everyone wants to
talk about. And here, so far, is the verdict: As of the other day, the
Community Bookstore, at least, still had a box full of umbrellas —
yellow ones, along with a green foldable and a black cane-handle that
had mysteriously joined their ranks.