Windows Phone 8.1, the next milestone for Microsoft?s mobile OS, is rumored to be announced April 2 in San Francisco, California



From WP Central:

Windows Phone 8.1, the next milestone for Microsoft’s mobile OS, is rumored to be announced April 2 in San Francisco, California. That’s only 7 weeks away, putting Microsoft on a tight schedule to line up all of their eggs for the big reveal.

One of those milestones is to open up the Software Development Kit (SDK) to developers for some initial feedback. Windows Phone Central has learned that Microsoft is now inviting a limited number of developers, under NDA, to begin early testing of the new 8.1 operating system and its SDK.

  Windows Phone 8.1: Microsoft quietly sends invites for confidential SDK Dev Preview program