• by Mark Walsh  @markfwal, April 3, 2009

Facebook has begun testing a new unit on the right-hand side ad space that shows up to five banner ads, exceeding the usual limit of three ads per page on the social networking site.

The wider format being tested with a small set of Facebook users also mixes content with ads, such as Facebook Pages which a user's friends have become a fan of, events friends are attending, or people who are friends of a member's friends.

Facebook on Thursday stressed that the new "module" was part of ongoing testing the company is doing with different ad and content placements and has not committed to running more than three ads on a page.

"It's accurate to say we've run a test, that in some cases has shown more than three ads, and it's part of a series of tests where we're intermixing content and ads in the right-side ad space," said a Facebook spokesperson.

An image of the format posted on the AllFacebook blog Thursday showed a rectangular unit containing five ads similar to Facebook's application ads -- with thumbnail images adjacent to the ad copy. AllFacebook's Nick O'Neill indicated that advertisers he had spoken to had mixed feelings about the test unit.

"While the advertisers confessed that they preferred the new layout format, they didn't like the increase in ads being displayed and they wanted more information about how the ads were being positioned," he wrote.

Placing more than three ads on a page could help Facebook generate more ad revenue per page, but the move also runs the risk of alienating users who are already unsettled by the social network's latest redesign. Facebook recently took steps to quell widespread criticism with the changes by taking steps to give users more control over information that appears in feeds they get from friends, companies and third-party applications.

At the same time, Facebook continues to seek out the right type of ads and mix of advertising and content to monetize its ever-growing expanse of online inventory. The company is now approaching 200 million active members worldwide.

Earlier this year, Facebook started testing the latest variety of its "engagement" ads -- polling ads that allows advertisers to ask users a question and solicit responses within the home page unit. Participants can then view the results and the responses of friends. Other types of engagement ads -- which run on the home page -- enable becoming a fan of a brand page on Facebook, commenting, giving a virtual gift, and RSVPing to an event.

In announcing the departure of CFO Gideon Yu earlier this week, Facebook said in a statement that it was pleased with its financial performance and "well positioned for the next stage of our growth."

And according to an internal Facebook memo cited by the D: All Things Digital blog, the company is on track to increase revenue 70% in 2009 and expects to be cash flow-positive in 2010. It also suggested that Facebook is headed for an IPO soon.

Market research firm eMarketer in December cut its 2008 estimate for Facebook ad revenue for the second time to $210 million from $265 million because of the weakening economy and hurdles to advertising on social networking sites.