The Tweet-Up — a talk by Stone followed by a Twitter-fed Q&A session — took place before a crowd packed to the rafters at the Cannes Lions International Advertising Festival, here on the Cote d’Azur.

Stone, who launched Twitter two years ago with fellow Google alum Evan Williams, said that their aim is to come up with a revenue model this year. So who is going to feed them the money that will make Twitter more than a cultural and geopolitical phenomenon? Companies — which are increasingly using Twitter to communicate with customers and prospects in real time — need to start paying for the unique service that Twitter provides, Stone suggested.

Among Twitter’s most active corporate users: Dell , JetBlue , and Whole Foods , which has almost one million followers. Stone and the other folks at Twitter — which now has a whopping 50 employees– are working hard to help companies understand the potential value of Twitter. Initially, Stone admitted, “We focused too much on tweets,” — and made people ask, “What the hell is a tweet?” Twitter’s pitch to companies has evolved to: “Here’s everything people are saying about your product.” Companies disagree and engage by tweeting.

Revenue generation would yield more than just a path to survival. “It would send out a signal that we’re building a company of enduring value,” Stone said. That signal, he added, will help attract more developers to create apps that will broaden Twitter’s appeal.

Sounds like Stone has been getting some serious advice on business-building. But further swatting down rumors that he and Williams might sell the company to Google or Facebook, Stone reiterated that Twitter is not for sale.

But he and Williams are open to partnerships. “There’s a sea of companies we’d like to complement and help,” he said. What does Stone say when someone suggests they’re a potential competitor with Twitter? “I say, ‘How ’bout we just be friends?'” – Pattie Sellers