Writers and other artists have long joined together to form coworking spaces, although they rarely call them that. They usually call them clubs or salons. San Francisco's Writers Grotto considers itself a club. But their description of their facility is very coworking like:
Since 1994, the San Francisco Writers’ Grotto has pioneered a unique concept: an office for the creative, self-employed people who by definition don’t need to punch a clock. From its beginnings, it’s been a place where narrative artists–writers, filmmakers and the like–welcome the discipline of structure in their work lives, and build a community of peers.
I love the NY Times description of the club. It starts with:
Anyone lamenting the dearth of surrealist literary salons in New York has only to stop by The Oracle Club, a new members-only workspace for artists and writers in Long Island City.
We have the same dearth in my town, but to be honest I haven't lamented it.
These clubs/salons are good examples of the growing trend towards coworking facilities targeted at specific vertical markets.