The shotgun marriage of Nokia and Microsoft's smartphone platforms puts software developers at center stage at the annual Mobile World Congress starting on Monday in Barcelona.

Last week, Nokia and Microsoft, the global leaders in mobile phones and software, announced a wide-ranging alliance which they hope will give them a chance of building an iPhone killer -- but it is still regarded as only a slim chance.

People had expected Nokia to fight back but the alliance won't be able to help Nokia rebound strongly. It will rather further consolidate the current trend of Android vendors gaining more market share, said Park Young-joo, an analyst at Woori Investment & Securities in Seoul.

Apple and Google's Android have already taken the high ground in the lucrative smartphone battle by attracting hordes of developers who make the small software applications, or apps, that make smartphones come alive.

Apple's iPhone was praised for its design when it launched in 2007, but it was its App Store that transformed the industry by allowing users to personalize iPhones with easy-to-install games, shopping aids and business tools.

Total sales from all app stores are expected to triple this year to $15 billion, research firm Gartner said last month.

Most developers are doing Android and Apple; they don't want to do anything else, even if they are paid for it. It's going to be very, very difficult for the others, said Magnus Jern, chief executive of mobile software house Golden Gekko.

The open-source Android software platform, unleashed on the market just two years ago by Google, has already stormed to the top of the smartphone platform popularity charts, overtaking Nokia's Symbian at the end of last year.

Device makers such as Samsung Electronics, HTC and Sony Ericsson have embraced it as it offers features and functions they could never hope to develop on their own as quickly.

On Sunday, Sony Ericsson and Samsung unveiled new models running on Android, with Sony Ericsson in a long-awaited move bringing Sony's PlayStation brand to the mobile market.

Samsung shares rose nearly 4 percent in Seoul on Monday following the launch of new products including an updated Galaxy tablet computer and on expectations of further gains in market share.

Its latest Galaxy tablet has a bigger screen and more processing power than the original. Some analysts see it as the only real rival to Apple's iPad.

The Galaxy Tab 10.1 is intended to be a multimedia hub for aficionados of games, electronic books and social media, with a 10.1 inch (25.7 centimeter) screen, dual surround-sound speakers, and front- and rear-facing cameras.

Many manufacturers will be trying to attract software developers at the Mobile World Congress in Barcelona with special events laid on for them.

A consortium of telecom carriers, who have so far largely failed to profit from the apps boom, will also launch their own app platform, named WAC, on Monday.

Operators are hoping their wholesale store -- from which operators' individual stores will take content -- gives them a scale which is big enough to battle with Apple and Google.

(Additional reporting by Miyoung Kim, Jungyoun Park and Hyunjoo Jin in SEOUL; Editing by Anshuman Daga)

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