Microsoft (NASDAQ:MSFT) CEO Steve Ballmer said the company plans to add "over 500 new features" to its Windows Phone smartphone platform later this year, additions the company will detail during a press event scheduled for tomorrow. Ballmer teased the news during a developer's forum in Japan, and said the company will provide additional information on Windows Phone handset makers and carriers during tomorrow's press event. Already, rumors indicate Microsoft's "Mango" Windows Phone upgrade will add third-party application multitasking, enhanced voice recognition and other features. Article