Yesterday Facebook raised the mobile stakes as it made its online gaming debut with the launch of a real cash  bingo app.

That’s clearly part of its much needed strategy to make money out of mobile, which will be key to Facebook’s future growth and revenues.

Another part of that strategy has also emerged and that is a new ad unit that will allow advertisers to promote their mobile apps on Facebook.

A much needed move by Facebook. The new apps ad unit joins sponsored Story ads, which in June Facebook announced it would be allowing advertisers to buy specifically for mobile for the first time.

Facebook first began selling mobile ads, which appear in users’ news feeds, earlier this year, following its inaugural Facebook Marketers Conference. However, advertisers were only able to buy them as part of a bundle with non-mobile placements, such ads on the right hand side of the page. That has now changed.

According to an Ad Age report the new ad unit will be targeted at different advertisers, namely those looking for users to download mobile apps, and will be priced on a cost-per-click basis.

“The promoted app will surface as a recommendation alongside apps that are being recommended organically based on a user’s history and social graph under the headings ‘Try These Games” and “Try These Apps’, but will be flagged with the text ‘sponsored’. Like any other ad, it can be targeted to users based on age, gender, location, likes and interests.

 Facebook declined to disclose its beta partners for the launch, but it’s safe to assume that plenty of game developers who depend on visibility and social sharing on the Facebook platform to market their games will be interested. For instance, Zynga partly attributed its weak second-quarter earnings in part to unforeseen changes on Facebook that led to a reduced number of “stories” about active games, which in turn cut back on the volume of users to feed its virtual-goods business.

 Facebook looking to social gamers for revenue is also nothing new. Zynga was the source of 15% of Facebook first-quarter revenue (through both ads and the cut it takes from payments made for virtual goods), according to Ad Age.