APPLE INC (AAPL) 199.92 -$0.59 (-0.29%) 01:31PM (15 mins delay)

In case anyone wasn’t counting, Apple’s App Store now has more than 100,000 applications. According to the press release, Apple (AAPL) has seen more than 2 billion downloads of those apps; my estimate is that that number is now about 2.4 billion worldwide. As we noted in our September report, Forecasting the Mobile App Gold Rush, we expect the U.S. will account for about 1 billion of those downloads in 2009; the rest come from around the world (and from 2008; Apple counts its app downloads since it launched its App Store in July 2008).

What’s behind all this app mania at the Apps Store? Well, for one thing, it’s not just iPhones driving this boom; iPod touch owners can run the same apps on their platform, and there are more than 20 million of those worldwide. But mostly this trend is because Apple makes it really easy for customers to both download and buy these apps. According to data from the Yankee Group Anywhere Consumer: 2009 U.S. Survey Suite, smartphone owners as a group download an average of 4.5 apps over the past 90 days. For Apple iPhone owners, that number averages 9.8, the highest of any smart phone manufacturer. Mobile ad network owner AdMob claims even higher numbers than that for iPod touch owners.