Facebook is rolling out two new sources of revenue: location-based ads and a mobile ad network for apps, according to The Register (News - Alert). The social networking giant has already revealed its “Find Nearby Friends” feature, which tracks the location of friends who happen to be nearby. Facebook (News - Alert) will also include mobile targeted ads within the new feature.

Facebook is also rolling out a system for developers to use in other apps outside of the social networking site.

The move represents a major shift in strategy for the company as users opt for more mobile devices and away from traditional desktop PCs. The company has been criticized for being relatively slow on the uptake in terms of mobile ads.

In 2012, only 11 percent of its advertising revenue came from mobile. In 2013, the figure rocketed to 45.3 percent, but the company faces stiff competition from Google, Apple and Twitter (News - Alert), all of whom have their own mobile ad networks.

Facebook’s platform allows advertisers to target users that are outside of the Facebook app and may not even have Facebook installed at all. Facebook already has a wide user base of nearly one billion users that advertisers will simply find irresistible. Combined with location-based ads, advertisers can more precisely target desirable demographics.

Of course, there are the inevitable privacy concerns. Fortunately, the Find Friends feature is strictly opt-in. Users who want to be found (and have ads targeted to them) will have to enable the feature in their settings.

The ad network might be harder to avoid. Lots of apps, including games, that are normally ad-supported offer ad-free paid versions. As with premium cable channels, perhaps the only way to really avoid ads would be to simply pay for the apps users really want and become the customers instead of the product, as they are for advertising-supported media.