iPhone App Accounts for 58M ,Facebook at 150 mobile users

Now, that's not to say that the 150 million users hitting up Facebook on their mobile devices do just that. There's no crossover statistic for how many of those are also logging into the service via the convention desktop PC or laptop route. However, it's interesting to note that—of these 150 million users—a significant chunk comes from those running the Facebook application via Apple's App Store.

And just how many is this? According to the official Facebook for iPhone page (on Facebook), there are 58 million monthly iPhone users at the time of this article's writing. This number is, itself, a bit less than 58 percent of the total devices running iOS on the market today—CEO Steve Jobs predicted that the 100 millionth device would be sold during June of this year.

"The Facebook application is by far the most important application on both the iPhone and the iPad," said David Kirkpatrick, author of The Facebook Effect: The Inside Story of the Company That Is Connecting the World, in an interview with The Motley Fool.

"It's the single most widely used application. It's so heavily used compared to other apps that I have been told by someone who thought he knew the data -- this is highly secret data and I don't know the actual numbers -- that more than half of all usage of the iPhone of apps, other than those provided by the phone itself like telephony and email, is coming from Facebook," he added.

As for Android-based mobile phones—which outsold Apple's iPhone in the first half of 2010, according to figures by Nielsen released earlier this month—4.3 million active users were recorded as using the Facebook for Android application within the past month. Facebook's Blackberry client attracted 29.4 million mobile users, the Facebook for Palm WebOS app is barely at one million users, and the Facebook for the T-Mobile Sidekick application isn't even half that.

Just to keep these numbers in perspective, however, the "Facebook for [phone]" statistics aren't correlated with the number of people that have actually downloaded the application onto any mobile device—it's just count those who have used the app to log into a Facebook account in the past 30 days. As well, there's no statistic yet released as to how many users log into the mobile version of Facebook via the Web, bypassing any apps altogether.

Facebook's last significant mobile milestone was announced in February of this year, in which the company detailed that 100 million users—of 400 million total—were accessing the site via mobile devices.