A Milestone 2 release of Windows 8 leaked publicly on Monday currently it is available in various private torrent and filesharing. The build happens to be an early sample of Microsoft’s work with the Milestone 2 stage of Windows 8which is compiled in February,So it relatively old copy of windows 8 so it does not contain improvments or features as present in 80xx builds .

With only few weeks away from Windows Developer Preview of Windows 8,The preview will likely contain a number of near final parts of Microsoft’s work with Windows 8 but will not mark the “beta” stage of Windows 8.We will be live from the BUILD conference from September 13 onwards, stay tuned for up to the minute coverage of Microsoft’s grand Windows 8 unveiling.

Source
Winrumor