The open-source Android OS is leading the charge in the mobile market, with a top share of 29% in January 2011. The mobile market landscape is expected to drastically change by 2015 however, and Android will become an even more prominent presence. IDC forecasts Android will capture 39.5 percent of the global market this year, and that this share will grow by another 12 percent to 45.4 percent in 2015.

Windows Phone 7/ Phone Mobile is also expected to see a tremendous amount of growth in the next 4 years, which is partially due to Nokia’s shift to the OS.

“Another significant finding from the new IDC report is that Windows Phone 7/Phone Mobile smartphone OS, currently ranked fifth globally with a small 5.5% market share, will catapult to the number two spot by 2015.”

Microsoft’s share of the mobile OS market is expected to increase by 380% to capture the number two spot in 2015 with a 20.9% global market. Symbian however is expected to drop by 99% to a market share of 0.2% within 4, years compared to a current share of 20.9%. The reason behind this is that Nokia essentially abounded its OS in favor of a partnership with Microsoft.

Despite the fact there are only a few thousand WP7 apps, Windows Phone 7 is still a better choice than Symbian. The partnership announced in joint letter by Nokia’s Stephen Elop and Microsoft’s Steve Ballmer, but there were certain concerns raised about the legitimacy of this venture. According to some sources, $1BN may have exchanged hands between Microsoft and Nokia in order to ‘ease’ the deal. Nevertheless, all this media buzz haven’t deterred Nokia from pursuing its plans, which includes an investment to provide a value-add to developers.

It’s Nokia and Microsoft vs. Google and Apple (and RIM). And, as a part of a much, much wider trend going on in almost every part of the tech industry, Nokia filed 7 new patent disputes against Apple.