We first found out about Project Astoria after some discovering the Android subsystem files on a build of Windows 10 Mobile.
Now, in the latest Redstone build of Windows 10 desktop similar files have appeared which suggests the OS will have access to a Linux subsystem also. The files, LXCore.sys and LXss.sys was discovered by prolific windows hacker Walking Cat who noted.
what the hell ? Windows 10 14251 has lxcore.sys and lxss.sys ? aren't they part of Project Astoria ? and for Mobile only ?
— WalkingCat (@h0x0d) January 28, 2016
The meaning of the find is still far from clear. Windows 10 desktop does not suffer from the same app gap (vs Linux at least) as Windows Mobile does, but Windows 10 Server may benefit from running linux-based server apps, so this may be related to the non-consumer side of Windows 10.
Alternatively this may still be related to Android apps and may be the return of Project Astoria, as Build 14251 is the first OneCore build of Windows 10, meant for Mobile, Desktop and Xbox One.
One of the reasons Project Astoria fell out of favour was that Android apps would only run on Windows 10 Mobile.. Making Android apps also Universal Apps may solve this problem.
Whatever the reason, I suspect a lot of scrutiny will soon descend on this bit of software, and the truth should be revealed soon enough.