For the first time, an agency-designed ad unit goes live on Facebook today. The unit -- called Comments -- is the result of an AdExpo Facebook held last year, where it gathered agencies and challenged them to create a new way for Facebook users to engage with brands. The comments from users and their friends have the ability to become a corresponding sponsored stories. Out of the 100 ideas submitted, Leo Burnett, Chicago's was selected. The move is part of Facebook's initiative to work closer with advertising agencies and creatives.

The unit -- the eighth available to advertisers on Facebook -- works by having the brand pose a question on the its Facebook page, aiming for a conversation-starter. That same question will also be posed in a traditional display ad on the right hand side of the Facebook screen. If users choose to respond to the brand's question, the conversation will move into the user's news feed, where it has the opportunity to be commented on by the user's friends. Brands hope to spark a lively, poignant or funny conversation that will have a life of its own. The comments from users and their friends have the ability to become a corresponding sponsored stories.

Hallmark plans to ask, "How do you make summertime a special occasion?" Allstate's "Mayhem" campaign will ask users, "What's your mayhem?"

"This unit allows a brand to introduce a conversation that can scale very quickly across our audience," said Facebook's VP-global agency relations, Blake Chandlee. "This is a perfect example of how brands and agencies need to approach Facebook differently."

Leo Burnett's chief innovation officer, Mark Renshaw, underlines how this approach is different. "Unlike in other advertising, we're not telling people how to think about the brand," Mr. Renshaw said. "We're just asking them to participate in the conversation."

The unit will only be available to premium accounts, and not in the self-serve product. The price is "the same as comparable Facebook ad units." The other seven units are Like, Poll, Sampling, Event, Video Comment, Application and Standard.

In an effort to work with agencies, in April Facebook launched a stand-alone community site, Facebook Studio, where ad-agency creatives can share ideas, comment on campaigns and learn what it takes to create a successful page for a brand. The community is called "Facebook Studio" and is a platform aimed at agencies, PR firms and media-strategy companies.

Almost a year ago, Facebook assembled a team to facilitate agency relations and started meeting with shops for the past to learn what they needed in order to work with Facebook. Along with the Facebook Studio site, Facebook is holding events called Studio Live, the first of which happened in New York last month.