NBC News has a great story on coworking. The video is short (2:05 minutes), focuses on the social aspects of coworking and is one of the best explanations of the concept I've seen.
NBC News SF also has a coworking story. It is on Cubes & Crayons, a coworking facility that also has daycare. It also does a nice job explaining coworking.
For those not interested in watching the video, an SF Chronicle story describes coworking as:
"Laptop nomads - that growing tribe of folks who can be found typing away at any cafe with wireless Internet access - are starting to put down roots. And some .... are doing it through co-working, a 21st century twist on the old idea of the shared artists' studio.
In co-working, a group of freelancers or other solo entrepreneurs share one big office space with perks that they might not get at home, such as conference rooms, espresso machines and opportunities for socializing."
For more info, see our category on coworking or visit the coworking blog