Mango, the largest update yet to Microsoft's still-young Windows Phone 7 mobile OS, was released to manufacturers Tuesday in what the software company called an "important milestone" in its fight to gain some ground in the competitive smartphone marketplace. The update was first shown off in May and is being viewed as a dramatic upgrade from the basic Windows Phone 7 platform, released in 2010. Mango sports over 500 new features and has a much greater focus on apps and communication tasks now regularly performed on smartphones.