The new format is dubbed an 'engagement ad', reflecting Facebook's expectation that it will prove more interactive for users than the standard ad formats it also offers.
The ideas in testing help make advertisers part of the community, according to Blake Chandlee, commercial director for Europe, and are designed to prompt actions that will show up in a user's friend's news feed.
Chandlee acknowledged that the Facebook community is more resistant to being served traditional ads than users of other more media-focused sites such as Bebo and MySpace.
"The whole concept of viewing and sharing is what Facebook is all about ... and the question is how do we as advertisers become part of that. We can't impose ourselves into it, it doesn't work that way," he said.
He believes the trial will help Facebook and its advertisers and agencies answer the question: "How do we get brands to interact with consumers in the same kind of way [consumers interact with each other]?"
As an example of the new format, Chandlee showed a mock-up ad for the Will Ferrell movie 'Step Brothers', consisting of a short video beneath which is a space for people to make a comment.
Once someone has commented on the video, whenever the ad is served to his or her friends they will see the comment and can add to it; in addition their news feed will show that their friend has commented on the ad. There is also a variation of this format that consists of a still or animated gif instead of a video.
The second type of engagement ad is an invitation to become a fan of a brand -- while the ability to do this by visiting a brand's page is nothing new, this simply allows the brand to go out across Facebook in the hope of recruiting users.
With the third already-familiar idea of giving a gift, Facebook is formalising the difference between 'normal' gifts such as a rose and advertiser-created gifts. It is promising only to distribute the latter through the engagement ad format.
Like Facebook's standard ads the gifts are charged on a CPM basis plus additional fees for the level of targeting an advertiser desires. There will not initially be a charge for the extra functionality.
The engagement ads will also be trialled in the US with 24 advertisers taking part, including Paramount, Adidas and Betty Crocker.
Facebook is currently offering users the chance to sample its new layout, which will be rolled out in the next few weeks.