I was a member of the first coworking space in San Francisco for a few weeks toward the end --- the one at Spiral Muse. I've also been to the (now defunct) hacklab here in Buenos Aires, to SuperHappyDevHouse (which is sort of an intermittent hacker space), to TechShop, to some classes at the Crucible, and gone to Wiki Wednesday at Citizen Space, and I'm considering signing up as a client of CoworkCentral here. So, given this broad but shallow experience, I think coworking spaces don't have much in common with hacker spaces; coworking spaces (IME) are a place where people go primarily to work (and aren't necessarily hackers, nor are they necessarily going to be happy with you interrupting their work to ask for help with your own), while hacker spaces are where they go to spend time with other hackers and work on fun stuff that you aren't getting paid for, in a fun collaborative setting. You might meet cofounders of a company at a hacker space and then go start your company in a coworking facility.

I recognize that my experience on both sides is pretty shallow, though.

noahlt writes: "Except maybe that coworking facilities already exist and work."

I'm pretty sure hacker spaces have been around a few more years than coworking spaces.