According to the reports by one of the members on the Chinese site ruanmei, Microsoft has started distributing Windows 8 on Connect to select beta testers. The build available on Connect is build 7971 which is the latest build known. To access the build you need an invitation code which is currently not available though the user at Ruanmei posted the following link-
The user states that he belongs to a major OEM company and they have just got the access to these builds. According to him, the program on connect is called as “Windows 8 and Server vNext Pre-Release”. If the information is true then we may see a leak pretty soon.