Mobile developers more than ever want to devote their energies to writing apps for Apple's iOS and Google's Android platforms at the expense of their less popular rivals, a study released on Wednesday showed.

Apple and Google, already the favorites among developers, are likely to gain even more traction thanks to game-changing new services, according to the survey from research firm IDC and Appcelerator, a company that works with app developers.

Millions are already signing up for Google+, the search engine company's infant social network that could present a formidable challenge to Facebook. As many developers plan to integrate Google+ as Twitter into their applications.

Apple is building momentum with its iCloud service, which will allow users to store music, video and other files in its remote servers and synchronize them on iPads, iPhones and other Apple devices. Even before its launch, iCloud has attracted as much interest among developers as Amazon.com's existing cloud-based service.

If you're not Apple and Google your task just became even harder, Scott Schwarzhoff, head of marketing for Appcelerator. Now you've got to think about what's my social and cloud strategy.

The moves make it more difficult for the likes of Microsoft, Hewlett-Packard and Research In Motion to bridge the gap and convince developers to invest time and energy in their platforms.

The number of respondents who said they were very interested in developing for each platform was little changed from last quarter, with iPhone at 91 percent and iPad at 88 percent. Android for phones rose slightly to 87 percent and Android for tablets recovered to 74 percent.

Interest in specific platforms drops off sharply after that, with 30 percent very interested in Windows Phone, 28 percent for BlackBerry phones and 20 percent for RIM's PlayBook tablet, 18 percent for HP's webOS-based TouchPad and 12 percent for its phones.

In fact, the fifth most popular option among developers (after iPhone, iPad, Android phones and tablets) is to build a web-based app using industry standards that can work across platforms, albeit with some loss of native capabilities.

That position between the leaders and the second tier was an interesting finding in terms of overall priorities, Schwarzhoff said.

The Financial Times launched a web-based version of its mobile app in June, the first major publisher to do so.

A quarter of respondents said Google+ will have the biggest impact on mobile growth and adoption, and two-thirds expect the search engine company to catch up to Facebook as a social hub.

Apple's iCloud, due to launch later this year, was seen having the biggest impact by 22 percent of those surveyed, and near-field communication (NFC) chips, which could turn phones into wallets, were rated most important by 18 percent.

The full Appcelerator report can be found at: http://appcel.us/q3_2011_report

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