Worth listening to if you live in San Francisco and have kids

"…in pursuit of revenue, Twitter faces the same challenge that has dogged social-networking platforms like Facebook. If advertisers can tap into its network free of charge, why would they pay the company to do so?

Twitter co-founder Biz Stone says the San Francisco start-up is watching the outside initiatives closely as it prepares to launch its own fee-based services this year, but doesn't view them as competition. "We want to work with those companies that are already making an effort," he says. "

Mr. Stone says Twitter recently hired a product manager to oversee the development of commercial accounts. The accounts would offer users more features in exchange for a fee, but Mr. Stone says Twitter hasn't set a launch date for them.