Facebook users on-the-go can now can share their actual, real-time location with their friends online. The popular social networking site just teamed up with Foursquare, Yelp, Booyah, and Gowallah -- four up-and-coming geo-location based sites --  to offer a location check-in platform to users in the United States.

It's like the store directory that you see at the mall: "You are here."  The new service is called "Places" and according to Reuters and the Facebook blog, this new feature gives users the option of letting people share where they are, meet up with friends and find out about events happening around them.

The service is a mobile application available as an iPhone app or users can go to touch.facebook.com, a website setup for touch screen smartphones that supports GPS auto-location.

To announce their presence at a physical location to their friends on Facebook, users will be able to tap a "Check In" button.  After checking in, users would then tap "Here Now" to see who else is checked in where they are.  That check-in will then appear on that location's "place page," on the users profile and in their friend's News Feeds.

Similar in a way to how Facebook's photo-tagging feature operates, friends can "tag" the friends they are with.

"This is not about broadcasting your location to the world, it's about sharing where you are with your friends," said Product Manager for "Places" Michael Sharon.

The social-networking site has been plagued by privacy issue concerns in the past.  And while the company has implemented a few guidelines that should put users at ease --  the default settings for check-in are visible to friends only and your friends can't start tagging you until you authorize it -- users should also know that their home could become a hotspot.  

Users have the ability to create new locations which means that if enough people check into that location, it will become visible to everyone.  Once it becomes visible to others, users would need to request that their home be taken out of the database.

"They want to make sure they've done their homework, because privacy does become a concern right out of the gate," said Altimeter Group Representative Michael Gartenberg. "They don't want to introduce this and then have to come back and fix it."

After receiving criticism from privacy advocates, Facebook provided new control options to its users in May. 

There are 500 million-plus active members on the popular site.