According to a report from Win8China, Windows 8.1 Build 9391 Developer Preview has been distributed to OEMs.
According to a report by Win8China, a brand new build of Windows, Windows 8.1 Developer Preview Major EEAP Build 9391 has been released to OEMs for testing. Apart from the build number and a special tag of "Developer Preview", not much is known about this new build from Microsoft.
We can speculate that this could be the exact build that will be released at Microsoft's Build 2013 developer conference due to its "Developer Preview" tag.
While Microsoft may follow the same route they took during the release of Windows 8, it is still unsure if Microsoft will also release a Consumer and Release Preview editions of Windows 8.1 for the general public.