The amount of mobile application store users will quadruple to more than 100 million in five years, according to a new report by In-Stat.

The report, titled "The Apps Store Is Born," said the boom is being led by Apple and its iPhone. The company's App Store has seen tremendous success since its release last year, and it has had more than 800 million downloads and more than 25,000 apps.

"With greater capabilities in both running native applications and viewing 'real Internet' Web sites, smartphones have increased usage and user expectations for mobile content," said David Chamberlain, In-Stat analyst, in a statement. "Along with the expanding handset base, users are downloading more applications."

The success of the App Store hasn't gone unnoticed by Apple's mobile rivals, and consumers will be facing a host of app store options in the near future. Google's Android Marketplace is already selling apps for Android smartphones, and Research In Motion's App World soon will be doing the same for its BlackBerry line. Microsoft's Windows Mobile, Palm's webOS, and Nokia S60 and S40 phones will have an app store later this year as well.

But merely having an over-the-air store for mobile programs may not be enough to attract customers and developers. Nokia will be integrating social and location-based features into its Ovi Store.

In-Stat sees the boom in app stores as a lucrative source of revenue for developers, as well as a new avenue for advertisers to reach consumers. While business models will initially be unclear due to nonstandard metrics, the research firm sees a bright future for strong marketers in these virtual stores.

"Reach for marketing applications is growing rapidly and those applications can provide prolonged engagement with the user and keep the advertiser's brand in focus," Chamberlain said.

InformationWeek has published an in-depth report on rich Internet applications. Download the report here (registration required).