Microsoft’s Windows Blue may have just hit milestone 1

The Windows team at Microsoft just completed the first milestone build (M1) of Windows Blue, the first full-fledged update to Windows 8, according to a couple of sources of mine.
windowsbluem1

One of my contacts said that M1 marks the half-way point in the Windows Blue development schedule. The last and final milestone build of Windows Blue will be M2, said this contact, who requested anonymity.