Will Fans Unfollow Ad.ly's Twitter-For-Pay Celebs?

The chance for two-way interaction with celebrities has been a strong driver of Twitter's growth, as passionate users like Ashton Kutcher and Oprah Winfrey have taken to the service with gusto. But will their followers' patience wane when those stars use Twitter to send out paid product endorsements and brand messages?

We're about to find out. As we reported last week, Kutcher's new Nikon deal calls for him to send sponsored tweets to his nearly 4 million followers. Now, TheWrap reports, the Ad.ly network is signing up a raft of B-list celebs, like Kim Kardashian, Dr. Drew, Nicole Richie and The Hills' Audrina Patridge with endorsement deals.

Companies hook up with the celebrity based on their prominence or stated interests. Once a celeb has approved a brand, that company will write the copy for an advertisement -- and even do the posting...

Offers are based on the number of followers the celeb currently has for his or her Twitter stream.

Celebrities with a big Twitter following have a powerful channel at their disposal. They've got their followers' permission to send messages on any topic of their choosing, 140 characters at a time. Mostly, celebs on Twitter deliver the goods, doling out details about their daily life, passing along funny pictures or recommended links, or rewarding followers by responding to their tweets. But if they want to use that channel for brand messages, they may be testing their fans' willingness to stay tuned.

So far, there's no sign of paid Nikon tweets on Kutcher's Twitter stream. But when they do appear, his followers will probably take it in stride: Kutcher updates often, frequently shouts out his most avid followers, and dialogues with his wife, Demi Moore. There won't be much backlash to the occasional sponsored tweet.

But the other, less-luminous celebs (Patridge boasts a "mere" 418,000 followers) may face a different picture, depending on whether their tweets seem forced or natural, and based on how aggressively they flog the brands they're paid to promote. If they let Ad.ly write their tweets, they risk sounding inauthentic -- a real hazard on social media (as seen in bloggers' outraged reaction to today's news that President Obama doesn't write his own tweets).

"It's an easy way to make money," Kyle Hulcher, a publicist for Ad.ly, told TheWrap. "It's a natural fit for celebrities because the more people who read you the more money you can make -- and they tend to have the most followers.

All well and good. But celebrities, brands, and new-school ad networks like Ad.ly need to remember that the first word in social media is "social." Users go to Twitter and other services to converse with people they care about, whether friends or their favorite stars. If the channel turns into a constant stream of brand messages, the conversation may relocate.