Lots of commentary in the blogosphere this week on 3-month-old start-up FON, which just received backing from Google and Skype, as well as Sequoia Capital and Index Ventures. FON provides a model for expanding wireless internet access across the world, by offering subscribers financial incentives for sharing their bandwidth. Their goal is to become the largest hotspot network in the world. Their model was described neatly by Ethan Zuckerman, who is on FON’s board of US advisers (and who will attend TED this year):

By joining FON, you agree to share your internet bandwidth with other users either as a “Linus” or a “Bill”. If you’re a Linus (ala Linus Torvalds), you allow your router to be open to other Foneros around the world, which, as FON spreads, means you’ll be increasingly likely to find free wireless access as your travel. If you’re a Bill (ala Bill Gates), you can charge people for accessing your bandwidth and split the revenues with FON. If you’re not a member of FON, you’re an “Alien” – you can gain access to a FON hotspot for significantly less than you’d pay to use TMobile or a similar public WiFi service.

Ethan also gives thoughts on why sharing WiFi’s a cool technology for Africa. TEDGlobal Producer Bruno Giussani provides context. And FON founder Martin Varsavsky explains his vision.