This year will be a big one for mobile applications, with the number of downloads for smartphones soaring two and a half times from 2009, a market research firm says.

Mobile application downloads will increase to just under 6 billion applications this year, up from an estimated 2.4 billion last year, ABI Research said. Driving the download frenzy are the rapid adoption of smartphones among consumers and businesses and the proliferation of app stores from manufacturers.

In addition, two new smartphone platforms are scheduled to make their debut later this year. Samsung's Bada operating system and Microsoft's Windows Phone 7 are considered similar to Apple's iPhone OS and will have proprietary application stores attached.

Despite the increasing competition, the iPhone is expected to continue as the leading app platform, with an online store of more than 125,000 applications offering niche and localized content, ABI analyst Bhavya Khanna said.

"Other platforms are still playing catch-up, with (Google's) Android being the fastest gainer among them," Khanna said.

With more than 30,000 applications available for Android-based smartphones, ABI expects more than 800 million applications to be downloaded this year for the platform.

While the number of downloads will soar, the opposite will happen with revenue from mobile apps, which will decline by 2012. That's because increasing competition is forcing developers to drop prices or go free using an advertising-based model, in order to stay on top of the download charts, ABI said.

In addition, handset makers, such as Nokia and Motorola, have started to bundle applications with phones to connect to popular social networks, instant messaging and GPS services.

Apple, which was the first out with an application store to support the iPhone, reported in January that downloads had topped 3 billion in the 18 months since launching the store. Apple's store is used by people in 77 countries and covers 20 categories, including games, business, news, sports, health, reference and travel.