Mr. Costolo (Twitter.com)

Okay, now we're really wondering what's up with Facebook's mobile strategy. Because--according to CEO Dick Costolo, anyway--Twitter seems to be doing just fine making money off mobile.

Reuters reports that Mr. Costolo appeared yesterday on a panel at a conference in San Francisco. Asked the difference between Facebook and its own company (we love it when moderators encourage beefs), he pointed straight to Twitter's mobile success. Apparently, in the last quarter, the company has generated more ad revenue on mobile than its website "on many days." Twist that knife, Dick:

"We're borne of mobile," Costolo said in response to a moderator's question about the difference between Facebook and Twitter. "We have an ad platform that already is inherently suited to mobile, even though we launched our platform on the Web and only started running ads on mobile recently."

Meanwhile, Facebook is playing around with mobile payments and "sponsored stories."

But Zuck's probably got a little breathing room to figure it out: Facebook reported $3.7 billion in revenue last year. Twitter doesn't report revenue, but estimates from eMarketer claim the company could make $260 million in 2012 and $540 million in 2014.

Unless, of course, shareholders get tired of the stock price situation freak out on him.