Seeds of Windows 7 Milestone have appeared on Mininova and The Pirate Bay, with the version number Windows 7 M1, Build 6519.1.071220-1520.
The size is 2.19G, released by a foreign organization named SoftZone. Previously, many similar versions of Windows 7 were leaked but all were considered counterfeit; this one, however, is believed to be highly authentic.