The KNICKERBOCKER GROUP was a group writing in and about New York during the first half of the nineteenth century. The name was made famous by Washington Irving in Knickerbocker's History of New York. Their association was one of geography and chance rather than of close organization.
Writers have always tended to flock together and form groups. Now with the internet, there need be no geographical boundaries, and our group can consist of writers around the world. A few groups I've noticed are the Blogger writers (more closely knit imho than the Wordpress writers), the indie ebook authors on Amazon forums, those on Facebook groups (I'm part of one of these and the constant email notifications are currently driving me insane), those all represented by a single literary agent, or published by the same publisher, those writing the same genres.... If you think about it, writing is such a solitary venture, yet we like to interact with other writers. Who else can really understand our peculiarities?
(This post has been inspired by and in some instances, directly quoted from A Handbook to Literature, 8th Edition, by William Harmon and C. Hugh Holman)