What is the difference between “real” celebrities and “online” celebrities when it comes to social media marketing? The real celebrities get paid.

Last December, social media guru Chris Brogan received a $500 gift card from K-mart to write an entire blog post about his visit to a K-mart store. Reality show vixen Kim Kardashian‘s rate? $10,000 per-tweet, according to Advertising Age‘s Michael Learmonth. Yes, you read that right. Ten. Thousand. Dollars. Per. Tweet.

Kardashian works with “in-stream advertising” company Ad.ly, which also includes Stephen Colbert, Lauren Conrad and Dr. Drew as clients. Derek Rey, co-founder of Ad.ly, told PRNewser today Kardashian “can command” $10,000 per tweet and that Ad.ly limits its “publishers” — as it calls Kardashian — to one paid tweet per day as to not alienate her audience. “We’re not a polluter,” Rey said.

How well is Kardashian, and other celebrity publishers selling? “We could sell out that inventory if we want to, but we have a lot of advertisers,” he said. “We’re filtering them before we go to our talent.”

The above Tweet from Kardashian sure reads like an advertisement, but contains no disclosure. Rey told PRNewser that Carl’s Jr. is not an Ad.ly campaign. Indeed, Kardashian just inked an endorsement deal with the fast food chain to promote their salads. Despite the fact that she is a public spokesperson, Rey told PRNewser that with any instance of one being compensated, “you have to disclose.”