A pre-beta build is expected to be previewed during the ongoing WPC 2011 according to various sources.

Microsoft is also said to start on the beta build ready by BUILD conference in September as soon as the WPC concludes. So hopefully we will see a build with the new Metro UI during the WPC, a beta build during the build conference and the RTM build by April 2012 if everything goes according to plan.

The Microsoft Worldwide Partner Conference (WPC) is an annual gathering for the Microsoft partner community to learn about Microsoft’s roadmap for the upcoming year, network and build connections, share best practices, experience the latest product innovations, and learn new skills and techniques.

Since 2003, the Microsoft Worldwide Partner Conference provides a unique five (5)-day event for thousands of partners from more than 130 countries worldwide, to plan their business strategies for the upcoming year.

This year the event will be held in Los Angeles between July 10 - 14 and will be centered around the success of Windows 7 and Windows Phone 7. A lot of expectation will be Microsoft revealing more information on their upcoming Windows 8 operating system and it's implication on the tablet market of 2012