With more than 540 million users who uses the social network through mobile devices (60% out of the user-base), Facebook knows it has no other choice than to storm on the mobile industry at least as the Invasion of Normandy. “Gather up the app developers troops,” says General Zuckerberg to his loyal lieutenants “and hand them the new Open Graph weaponry.”

And so, after other Open Graph features such as Built-In Follow and Like actions have been delivered to mobile app developers for a deeper integration with the social network, the Allied forces of Facebook now brings another sort of artillery into the mobile battlefield, Mention Tagging.

The company announced that developers can now implement a new feature in their apps which will allow users to tag their Facebook friends within the app’s own text message itself. For example, whenever a user check-in on Foursquare and types some of friend’s name on the message box, it can be linked into the friend’s Timeline profile (as in the image on the top).

After the friend has been tagged, he/she will be notified and if they enabled it on their privacy setting, the post will appear on their Timeline (or will pend approval if set so). If non-friends have been tagged, they will have to approve the post regardless to their privacy settings before appearing on their Timeline.

In addition to the wider distribution of the social network’s reach across the mobile ecosystem, the Mention Tagging feature suppose to increase the engagement of users with the social network as people will have easy clickable possibilities to pry more conveniently into their close connections’ (or others’) social lives OUTSIDE of Facebook.

If the Mention Tagging feature will indeed get adopted widely by app developers, that will be another step of Facebook to establish itself as the unofficial default social networking identity of the web. Even when people are using external third party apps, Facebook’s features and tools are intensely rooted inside.

For app developers, the big upside of the feature is that it will provide the app a more intimate sentiment for users which will encourage them to reuse it. Additionally, the feature is obviously another way to broad the range of the app to more audiences.

If you are an app developer and you want to implement the Mention Tagging feature inside your app, be sure to read its documentation thoroughly so your actions won’t be denied due to some guideline violation.

And “Attack!” shouts General Zuckerberg.