• by Mark Walsh  @markfwal, April 13, 2010

Underscoring Facebook's rapid mobile growth, the social network's application from GetJar has been downloaded more than 50 million times since launching in the mobile app storefront six months ago. The next most popular app in that period has been that of Internet messaging service eBuddy, downloaded 20 million times.

Rather than a full Facebook application, GetJar provides a small app that gives users one-click access to the social network's mobile Web page from their handset. Facebook in February surpassed 100 million active mobile users worldwide, equal to a quarter of its total user base.

"With more than 400 million users around the world, people are increasingly looking to stay connected through Facebook from their mobile device," said Alison Rosenthal, head of mobile business development for Facebook, in a statement. "GetJar has helped us bring the Facebook mobile experience to more than 50 million people regardless of their mobile platform, phone model or carrier."

In addition to its m.facebook.com site and another site tailored to the iPod touch, Facebook has also launched apps for key mobile platforms including Android, BlackBerry, iPhone, Nokia and Samsung. It also has versions geared to devices from manufacturers such as HTC, LG Electronics and Sony Ericsson as well as a text-only mobile version of its service called Zero. Overall, Facebook works with 200 operators in 60 countries to distribute and promote its mobile products.

The m.facebook.com site has 19.8 million monthly active users, according to new data from Inside Facebook. But that's still far less than Facebook's iPhone app, which boasts 31.4 million users. BlackBerry's Facebook app is the next most popular, with 15.9 million. Building on its success on the iPhone, Facebook is also expected to introduce an iPad app soon.

Predicting an "app gold rush," market research firm Yankee Group last month nearly tripled its projection for total U.S. mobile app revenue in 2010 from $537 million to $1.6 billion. By 2014, that figure is forecast to grow to $11 billion.

Independent app store GetJar offers about 68,000 mobile apps and is approaching 900 million downloads. It works with partners including Sony Ericsson, Sprint, Opera, Vodafone, 3UK and Virgin Mobile.