Fon has been around for awhile. Which is to say, three months. The Spain-based brainchild of Martin Varsavsky, it's a global community of people who share WiFi connections. Also a business. And it's about to get a lot bigger, because Google, Skype and Sequoia Capital have just invested $21.7 million in it. And if you're a "Linus", a "Bill", or even an "Alien", Martin explains, you get to benefit too. Or that's the idea, anyway.