Winforum.eu's message board posted the image earlier today (whch we are not showing here here) which shows that the build number has gone up to version 9385, with the date of April 12th. The forum claims that the build was made available via Microsoft's partners on Sunday, April 14th and is the 64-bit ISO.

At the moment, there's no evidence that this newest build of Windows 8.1 has actually been leaked. However, if this information is correct, it shows that Microsoft continues to make steady progress on this major Windows 8 update. Microsoft is expected to launch a public preview of Windows 8.1 at its BUILD 2013 conference in late June, followed by its official launch sometime later this summer.