We had published about her leakage of Update 1 of Windows 8.1. As of today it is available for download for those who want to take an early look at the characteristics of the next major Windows update.
ISO only comes in the form of 64-bit and brings several changes to Windows 8.1.
The full build number of ISO leaked is 9600.16596.WINBLUES14_GDR_LEAN.140114-0237 and is exclusively compatible with 64-bit systems. Its version of 32-bit will probably soon leak.
Of course, it would be good to know, that this is an early build, and it could be very unstable and with quite errors which could affect its overall performance computer your. The official release is scheduled for March.