How will Twitter make money? It's the $500-million question (the amount, mostly in stock options, that Facebook reportedly offered to buy Twitter) that has plagued the company since its rise to prominence.

Potential investors and technology analysts are notoriously cynical of Web start-ups that haven't yet established a business model. YouTube and Facebook were pelted with those same criticisms in the past, and now, the skeptics are demanding the same from Twitter -- shake your money maker.

Twitter co-founder Biz Stone finally has an answer. By charging for corporate accounts, Stone says, Twitter will earn revenue from such companies as JetBlue, Comcast and Dell, which already use the social networking tool to build brand awareness and grassroots advertising. In exchange, Twitter will work with these companies to build corporate-exclusive features.

Stone described one such feature -- an identity verification tool that would allow anyone to discern easily whether a particular account is, indeed, owned by the person who the user claims to be.

"Like, users who want to know: is that the real Shaquille O'Neal or not?" Stone said. "Maybe we could help users by saying, Yup, definitely the real Shaquille O'Neal. That's a real account. We checked with them."

This could have come in handy last month when technology bloggers wondered aloud whether @theRealAlGore was actually, well, the real Al Gore. (It wasn't. But @algore is.)

Stone wouldn't go into detail about other features, but says the company has plenty of ideas kicking around. However, he was clear about one thing: Advertising is not the route they'll take. At least, not any time soon.

But just because Twitter won't place ads on its pages doesn't mean others aren't trying. Twittad allows users to ...