Social networks came into existence thanks to our instinctive need for sharing. Facebook grew out of college campuses by allowing students to share photos or "faces", while Twitter grew by enabling users to share short and quick "tweets" or status updates. As smartphones like iPhone and Android led to the rise of the mobile web, location signature of GPS-enabled devices added a new twist. Users could share locations and activities, opening up a wide range of possible applications, and creating brand new specialty social networks.

As I recently moved from OpenSocial to the Geo APIs, I'm very excited to see that Google Maps is the default platform to power this fast growing segment of what I call the Geo Mobile web. In this post I'm going to highlight this emerging trend by sharing a few of my favorite examples.

Let's start with FourSquare, which is all about sharing the location and activities of users. When a user signs in from a mobile device, FourSquare detects the current location of the user, performs a reverse geocode to fetch a list of places nearby and sends them back to the user, who can opt to check in at one of the places and share it with others. In this snapshot the Google San Francisco office is shown on Google Maps using the Google Maps JavaScript V2 API. Users can check-in to a place, see check-ins by others, explore places nearby, and build up social contacts by adding friends, all the while having fun by earning badges.

Gowalla by Alamofire is another application building on this same concept of user check-in and sharing location and activity. When a user chooses a place of interest, activities by others at that location are shown and the user can choose to add people as friends, discover new places, pick up, drop off, and trade items with others.

Gowalla's web app version uses the Google Static Maps API to show a map view of a place while the iPhone native app uses the MapKit framework to render a map.

It is interesting to note that users of these apps initially start out without a built-in social graph but can gradually build them up by sharing their own whereabouts and discovering the location and activities of others.

This kind of viral sharing has boosted the growth for Facebook and Twitter in the past and it is once again driving the creation of these specialty social networks on the new frontier of the Geo Mobile web.

Established social networks like Twitter have taken notice. They recently enhanced their APIs by offering geotagging for tweets and local trends, which have spawned innovative mash-ups like Trendsmap.

The rise of these specialty social networks on the Geo Mobile web is predicated on the introduction and wide adoption of smart mobile devices, the viral spread in user sharing check-ins, as well as the availability of geo data sources and services. Google Maps is the developer solution of choice for many of these applications in regards to data source of tiles and places and services like geocoding, and I'm looking forward to seeing more innovations in this exciting arena.

Posted by Shawn Shen, Developer Relations