• by Mark Walsh  @markfwal, March 16, 2009

Facebook has extended Facebook Connect beyond the desktop to the iPhone, allowing mobile developers to create mobile applications that tie into the social network.

Launched in December, Facebook Connect lets members log into third-party sites using their Facebook account. User information from the social network can be imported to other sites, and activity on other sites is shared with Facebook friends via feed stories. So far, more than 6,000 sites have adopted Facebook Connect.

The new service capitalizes on the popularity of the iPhone and iPhone apps to promote increased social interaction and sharing on mobile devices. "We are excited to see Facebook Connect going beyond the Web to even more software experiences no matter where they are," wrote Josh Elman, a platform program manager at Facebook, in a post Monday on the Facebook Developers blog.

The company formally announced the iPhone initiative over the weekend at South by Southwest in Austin, Texas. It comes on the heels of Facebook's rollout of a revamped home page and brand pages (now called public profiles) as part of a wider strategy to make content-sharing faster and easier.

Among the first iPhone apps and games to integrate Facebook Connect are Agency Wars, Binary Game, Live Poker, Whrrl, and Urbanspoon. Many more are expected to follow.

"Facebook Connect for iPhone is a big step forward in the advancement of the social Web because it bridges the social graph, identity, and privacy of Facebook with the rich, mobile application platform of the iPhone for the first time," wrote Justin Smith, founder of the Inside Facebook blog, in a post Monday. He predicts developers will be eager to create apps that take advantage of Facebook features like the news feed and invitations to boost viral distribution.

Mobile social network Limbo is among developers already on board. "Our members want a new way to share their experiences from their iPhone or iPod touch with friends who may not yet be Limbo members," said company CEO Jonathon Linner, in a statement. "Now that Limbo features Facebook Connect for iPhone, they can easily share and distribute information and experiences with their friends via Facebook status updates, requests and notifications.

Apple offers more than 25,000 iPhone apps through its App Store and says that more than 500,000 have been downloaded to date.

In a related move, Facebook has also announced the latest round of the fbFund competition for developers building apps on the Web, iPhone and any other platform with Facebook Connect. Up to 50 developers will be selected as first-round winners in May. After that, several finalists will be awarded $100,000 each in equity investments and given the chance to participate in a new incubator program run by Dave McClure of Founders Fund.

Facebook's Elman also said in his post that Tweetdeck--a popular desktop application for tracking updates on Twitter and other social media services in one place--now also includes Facebook. So users can monitor Facebook status updates on Tweetdeck as well as post to Facebook and Twitter, or both simultaneously.