One factoid, however, deserves a big footnote. Introducing the hyperlocal landscape, CUNY's Jeff Jarvis said there are "a thousand blogs in Brooklyn alone."
There may well be that many, but only a handful or two or doing journalism (and many more conveying information in various forms). So, despite the apparent nation-leading concentration of blogs, Brooklyn hasn't yet produced a blog news network, nor should it be expected to do so.
Brooklyn College journalism professor Paul Moses has said, "Nowhere in the country do so many people get so little local coverage." And blogs--at least in the current configuration--haven't changed the situation enough.
The "bloggiest" background
Jarvis's source for the factoid, I believe, was Outside.in, which has a curious history of assessing blog metrics.
In an April 2007 claim that made national news, Outside.in said that Clinton Hill was the nation's "bloggiest" neighborhood, a meme that has stuck.
However, the source of that claim--as Outside.in leaders later acknowledged--was all the blogging about Atlantic Yards, a project located not in Clinton Hill but in Prospect Heights.
And, for what it's worth, none of the blogs with the most content about Atlantic Yards--No Land Grab, this blog, DDDB, and Noticing New York--have a business model. (Well, DDDB is raising money.) The controversy over Atlantic Yards is a quite a motivator.