Your points are fair, but color with the fact that the Windows Subsystem for Linux (WSL) is build to be distro-agnostic. We picked Ubuntu in this first version due to its popularity with developers, but there are few technical reasons (other than us fully and accurately implementing the necessary syscalls) why it shouldn't support other distro's userland environments in the future. Knowing this, what should we call it? Windows Subsystem for Running POSIX + Linux Syscall API Compatible Userland Tools? WSRPLSACUMT? 
I'm genuinely interested on what you all feel would be a good way to think about naming moving forward.
No - this is a whole new thing. The Windows POSIX subsystem which shipped in NT 3.5.1 was a minimal implementation of POSIX syscall API plus a userland toolset. That was replaced with Interix which was renamed Services for Unix (SFU) which had a more comprehensive kernel implementation and more up to date userland. However that tech was not resurrected to build the Windows Subsystem for Linux (WSL). Importantly, WSL doesn't ship with a distro - we download a genuine Ubuntu userland image at install-time and then run binaries within it.
Yes - Cygwin is essentially the GNU tools recompiled as Win32 apps using a helper library for shared code etc. Windows Subsystem for Linux (WSL) which underpins Ubuntu on Windows is new Windows kernel infrastructure that exposes a LINUX-compatible syscall API layer to userland and a loader that binds the two. This means you can run real, native, unmodified Linux command-line tools directly on Windows.
Want to make this absolutely clear - this is a command-line only toolset for developers. It is not built to support GUI desktops/apps. It is not built to run production Linux server workloads. It is not suitable for running micro-services or containerized environments. Again - this is A COMMAND-LINE-ONLY DEVELOPER TOOLSET!
Соус:
Для тех, кто нипанимат.
Бедный, кривой и больной POSIX решили выпилить из 10ки и впилить нормальную и полноценную совместимость, чтобы не юзать костыли, типа mingw -) Радует, что реализации будут так же, сразу в кернеле, соотв. сильной потери скорости не будет. Теперь писать кроссплатформенные приложения станет проще, гип-гип УРА!
I'm genuinely interested on what you all feel would be a good way to think about naming moving forward.So do Cygwin and/or MSYS emulate the fork()
Yes. That's one thing we spent considerable engineering effort on in this first version of the Windows Subsystem for Linux: We implement fork in the Windows kernel, along with the other POSIX and Linux syscalls. This allows us to build a very efficient fork() and expose it to the GNU/Ubuntu user-mode apps via the fork(syscall). We'll be publishing more details on this very soon.In other words, they're not using «Linux» at all. It's an Ubuntu userland on top of the Windows kernel, similar to how Nexenta was an Ubuntu userland on top of the OpenSolaris kernel.
You pretty much nailed it No - this is a whole new thing. The Windows POSIX subsystem which shipped in NT 3.5.1 was a minimal implementation of POSIX syscall API plus a userland toolset. That was replaced with Interix which was renamed Services for Unix (SFU) which had a more comprehensive kernel implementation and more up to date userland. However that tech was not resurrected to build the Windows Subsystem for Linux (WSL). Importantly, WSL doesn't ship with a distro - we download a genuine Ubuntu userland image at install-time and then run binaries within it.
Yes - Cygwin is essentially the GNU tools recompiled as Win32 apps using a helper library for shared code etc. Windows Subsystem for Linux (WSL) which underpins Ubuntu on Windows is new Windows kernel infrastructure that exposes a LINUX-compatible syscall API layer to userland and a loader that binds the two. This means you can run real, native, unmodified Linux command-line tools directly on Windows.
Want to make this absolutely clear - this is a command-line only toolset for developers. It is not built to support GUI desktops/apps. It is not built to run production Linux server workloads. It is not suitable for running micro-services or containerized environments. Again - this is A COMMAND-LINE-ONLY DEVELOPER TOOLSET!
Соус:
Для тех, кто нипанимат.
Бедный, кривой и больной POSIX решили выпилить из 10ки и впилить нормальную и полноценную совместимость, чтобы не юзать костыли, типа mingw -) Радует, что реализации будут так же, сразу в кернеле, соотв. сильной потери скорости не будет. Теперь писать кроссплатформенные приложения станет проще, гип-гип УРА!
ещё чучуть и можно полностью переходить на *nix 
как же я буду жить без недо ОС от гейца
