Microsoft’s much anticipated Window Phone 7 went on sales in the USA yesterday. The launch, which was a culmination of $100 million ad campaign, featured rock concerts at San Francisco and New York backed up by celebrity “glamour” power. Microsoft is hopeful that the glitzy launch will not only heighten initial sales, but will also  act as a statement heralding Microsoft’s return to the mobile OS market.

Windows Phone 7 comes equipped with Microsoft’s “Metro” user-interface. The new interface features large colorful tiles for Facebook updates, photos, e-mail messages and calendar items. The home screen, called the "start screen", is updated constantly with fresh information. According to Microsoft the continuous flow of information makes it easier for users to get in and out of their phones quickly, and will “help people break their zombielike fixations with their phone screens”. In the words of Microsoft’s CEO Steve Ballmer, "we want to let you get in, out and back to life as fast and simple as humanly possible”.

Apart from the Metro interface the new system includes all the latest Microsoft gizmos, including a web browser, MS Office support, Xbox Live hook-up, Bing search engine & maps along with full range of multi-media support.

Microsoft has a lot of catching up to do with the new system. According to International Data Corporation, a research firm in Framingham, Massachusetts, Nokia is presently the undisputed leader of the cellphone OS industry. The Finnish company holds 40% of the overall market share with its Symbian OS systems. Blackberry is in second place with 18% of the market, closely followed by Google Android and Apple iPhone with 16%, and 15% of the market share respectively. Microsoft, an industry leader of yesteryears, is on the fifth spot with less than 8% market share.

Initial reviews have been good, however only time will tell as to how the new smartphone OS fairs in the market.