I don't think we should kid ourselves that "local" is always more efficient (or "green"). If you're looking to prototype, it's a great tool, but larger 3DP machines are still more time-cost efficient due to how parallel the production can be.
*Full Disclosure, my startup: http://CloudFab.com works on 3D printing in a more centralized production model, but I still think MakerBot is awesome!
*Full Disclosure, my startup: http://CloudFab.com works on 3D printing in a more centralized production model, but I still think MakerBot is awesome!