Microsoft already previewed some of thecoming to Windows Phone via its impending Mango update, but it looks like that's just the tip of the iceberg.
Speaking at the Japanese Microsoft Developer Forum 2011, Microsoft CEO Steve Ballmer revealed that the company has added more than 500 new features to its mobile operating system, which are set to be unveiled at a special preview event in New York on Tuesday.
Ballmer also noted that the company will share information on who will build new Windows Phones, indicating that we might hear about some new hardware at tomorrow's press conference. That said, don't expect the devices or the Mango update to be available right away, as they're expected to hit "later this year."
Previously at, Microsoft divulged that the Mango update will also bring such features as third-party multitasking, Internet Explorer 9 support, and Twitter integration in the Peoples hub. We'll be at the Windows Phone preview event tomorrow to bring you all the action, so be sure to check back at 7 a.m. PT to follow along and participate in our live blog.