All About Microsoft posted a news story that the next version of Windows Phone is most likely 7.5
When I received my first tip about the “Mango” Windows Phone release — back in December 2010 — my sources said the update might ultimately be named “Windows Phone OS 7.5.” It’s looking like that is Microsoft’s plan, based on the company’s own partner information page (as spotted by the WPCentral.com site on April 22).Microsoft expected to go with Windows Phone 7.5 for Mango
Mango is the next major version of the Windows Phone operating system — one that will bring IE 9 Mobile; application multitasking; Twitter integration; and access to a SQL database for the phone. Developer tools for the Mango update are slated to arrive in May 2011, officials said earlier this month.