Social networking is one of the fastest-growing activities among mobile users around the world. And as one of the primary ways mobile users communicate with one another, it is proving a significant driver of Internet usage on mobile devices.

eMarketer predicts the number of mobile users accessing social networks from their mobile devices will reach 607.5 million worldwide by 2013, representing 43% of global mobile Internet users. In the US, mobile social networkers will total 56.2 million by 2013, accounting for 45% of the mobile Internet user population.

“Combining two much-hyped, but still-emerging channels—mobile and social—results in a developing opportunity for marketers,” said Noah Elkin, eMarketer senior analyst and author of the new report, “Mobile Social Networks: Marketing by Location Shows Potential.”

The big three destinations of Facebook, MySpace and Twitter dominate the US mobile social networking space as they do the desktop world.

Location-based networks such as Loopt and foursquare have not yet reached critical mass, but are worth keeping an eye on as they work to link people, places and interests. In addition, location-based services can also be used in other contexts to help marketers target social network users with relevant information and offers.

“Location-aware branded applications and utilities that include a social component provide an avenue for marketers to engage their audience directly,” added Mr. Elkin.

But the combination of two emerging channels means that estimating the market for mobile social advertising and marketing is premature, despite the promising user base.

Marketers are talking a lot about social and mobile and, on a slightly smaller scale, preparing to incorporate both environments into their marketing mix. But since both channels are still evolving, combining mobile and social together puts many marketers into a gray area from both a budgetary and oversight perspective, and programs remain small and experimental.

The full report, “Mobile Social Networks: Marketing by Location Shows Potential” also answers these key questions:

• Who are the mobile social networkers?
• Are consumers interacting with brands on mobile social networks?
• What is the outlook for location-based services?
• Is there an opportunity for marketers to use social networks to reach mobile consumers?

To purchase the report, click here. Total Access subscribers, log in and view the report now.

Check out today’s other article, “Web Users in France Trust Internet Most.”