The industry has been waiting for Facebook’s version of AdSense for years now, and now, as a public company looking to increase revenue, we may be getting closer to seeing this come to fruition.

In June, InsideFacebook reported on a possible hint at such a network on Zynga’s site, which was displaying Facebook ads and sponsored stories. At the time, Facebook said, “We have had a close relationship with Zynga for a number of years and we think we can deliver value to Zynga and to the people playing their games by showing the same ads that they see on Facebook. We will not be showing ads on other sites at this time.”

Now, reports are coming out that Facebook is testing a mobile ad network. Marketing Land shares a comment from the company, which says, “We are working on a small test in which we’ll be showing mobile ads in apps off of Facebook. We’ve been showing web ads off of Facebook on Zynga.com for a few months now and we think that showing mobile ads outside of Facebook is another great way for people to see relevant ads and discover new apps.”

Yep, that sounds like the beginning of something much bigger. While it’s only a test at this point, only on mobile, and only in apps, it’s easy to imagine that this will expand to not only apps but websites across the web on both mobile and desktop. I mean, why not? Facebook is already integrated into sites all over the web.

According to Pamela Parker at Marketing Land, the company is working with a small number of undisclosed ad exchanges to serve ads on iOS and Android.

TechCrunch reports that the ads are targeted based on users’ biographical and social data within non-Facebook mobile iOS and Android apps, as well as mobile sites where you’ve authenticated Facebook.