Twitter, the latest social networking craze, may eventually go to the stock market for funding if necessary, its co-founder Biz Stone said yesterday. The three-year-old company was already making some revenue, he added, and would concentrate on growing that next year. “2010 is really going to be the revenue year. I don't know if we're going to be profitable, but we have plenty of time," Stone said yesterday. In September, Twitter received a new round of funding from investors including mutual fund giant T. Rowe Price and private equity firm Insight Venture Partners, which analysts said set the stage for an eventual IPO or sale.