Worldwide mobile application store downloads are set to reach 17.7 billion downloads in 2011, a 117 percent lift from an estimated 8.2 billion downloads in 2010.And, according to researcher Gartner, by the end of 2014, more than 185 billion applications will have been downloaded from mobile app stores since the launch of the first one in July 2008.

Worldwide mobile application store revenue will surpass US$15.1 billion in 2011, both from end users buying applications – and applications generating advertising revenue for their developers. This is a 190 percent increase from 2010 revenue of US$5.2 billion.

Gartner says the hype around application stores in 2009 continued through 2010 with alternative offerings to the Apple App Store gaining some traction. Players such as Google’s Android Market, Nokia’s Ovi Store, Research In Motion’s App World, Microsoft Marketplace and Samsung Apps were the key competitors that saw their number of application downloads grow in 2010 – but Apple remained the giant.

Free downloads are forecast to account for 81 percent of total mobile application store downloads in 2011.

This percentage has been decreasing since the first launches in 2008, and Gartner estimates free downloads will continue to decrease in 2011, but should increase again from 2012 through 2014.

However users will begin paying for more applications as they perceive value in the concept of mobile applications, and they become more trustful of billing mechanisms, the researcher says.

By the end of 2014, Gartner estimates advertising will be responsible for a little under a third of the revenue generated by application stores, up from 16 percent in 2010.

“Many are wondering if the app frenzy we have been witnessing is just a fashion, and, like many others, it will pass. We don’t think so,” says Stephanie Baghdassarian, research director at Gartner.