I asked Tara for a clarification on the subject and this is her definition "Coworking is about both sharing space and collaboration -- whichever you need that day. :)"
Part of it is sharing resources (office equipment and so on) and space but maybe as important as the financial advantages is the social aspect.
The human interaction, the ability to put your ideas to the test and gain from the talent pool surrounding you allows you to focus on your strengths and 'outsource' some tasks you are not very good at to others located a desk away.
Tara Hunt is one of the residents at Citizen Space in San Francisco. In the US, similar facilities exist in New York (116 West Houston), Portland (Cube Space), Denver (The Hive)and Philadelphia (Independents Hall), to name a few.
At this stage, I am personally more looking at Coworking in the collaborative sense, graphic design would be the first thing I would think of.
We also might need an office or a desk for a short time while we travel. As Tim Ferriss says Coffee Shops have their limits. Sometimes we need peace and quiet. Since he travels a lot, Tim recently signed up for the American Express Business Platinum Card which offers a number of perks including access to office space in some 400 cities around the world.
More on Collaboration: Southern Europe offers more than Sun