We are continuously reporting about the latest leak or any new feature which is found in Windows 8.
Beta archive has reported that they had got the first Milestone Leak and they had put on their private FTP server for the download.
The complete build number of this leak is 6.1.7850.0.winmain_win8m1.100922-1508.
Update :- I had searched a bit and found the same leak on Torrent site, but we advice you to stay away from such leaks as they may include some malware in it.