Call it the Apple App Store effect, says the on mobile storefronts. Despite having one of the smallest catalogs of all the development platforms -- now around 15,000 app titles compared to 85,000 each for Palm and RIM -- Apple's iPhone App Store has generated significant sales across the board.

"Apple did a lot for the market [last year] with its massive marketing effort telling the public how great mobile content is," said senior analyst Jeff Orr in a news release. "That created a 'halo' effect for the rest of the industry: other device manufacturers and content developers working on non-Apple platforms all saw a bump in sales and downloads because there's more awareness of the smartphone category."

As a result, this year more mobile application storefronts will be launched from Nokia, Palm, RIM and Samsung, said Orr.

The study, conducted in November, asked 235 U.S. smartphone users who installed applications on their devices in 2008 how much they had spent in the last 12 months. ABI found that almost 17 percent doled out between US$100 and $499 for mobile apps. The majority spent between zero cents and $100.

Considering how cheap most mobile apps are, starting for as little as a buck at Apple's App Store, that translates into a lot of downloads. There has also been a lot of excitement about mobile apps thanks to Apple heavily marketing its App Store for the iPhone and iPod Touch.