Last week I wrote on Facebook's lost youth.  Just as the NYTimes and every social blogger from Silicon Alley to the Silicon Valley is proclaiming Facebook's web death, I think we have missed a growth trend.  25% of Facebook's usage, which is one in four users, approximately 65 million people are engaging via their mobile phones.

Facebook has two mobile web sites: m.facebook.com, which works on any mobile browser, and x.facebook.com,
which is designed specifically for touch screen phones like Android,
Palm, iPhone and Nokia. These sites have been translated into more than
60 languages and allow you to update your status, browse your news feed
and your friends' profiles, comment or "like" stories, and view or
update your Facebook Page.

In addition, the recent launch of the Facebook 3.0 iPhone app has renewed interest as the functionality goes far beyond the old browser based functions.

I remember the first mobile version of Facebook, which launched in 2006, was merely a status update (like twitter) and photo upload tool.  Eight months ago, Facebook mobile had climbed to 20
million active users, thanks to the explosion of smart and touch screen phones like the MyTouch 3G, iPhone, BlackBerry, Windows Mobile, Nokia, HTC,  Sidekick, and countless other handsets.

Facebook's future may lie somewhere in between revitalizing the oldest social tool on earth (the phone) and becoming the largest mobile computing platform.

Sources: Facebook Blog, Silicon Alley Insider & AOL Tech