>>"But they're all just "Linux". I don't see the point in saying that they ported to this distro and that one when they're all essentially the same target assuming they use standard tools like autoconf."
Actually, this is a bit of a red herring. What Microsoft did was create an Open Source service and provide it as package for these distributions and the package is designed to allow people to manage those OSs using Powershell from a remote machine. They haven't ported Powershell itself to GNU/Linux and that wouldn't really make sense as Powershell is OO-based and GNU/Linux exposes little to none of itself as objects. The package is more like a proxy way of configuring things, monitoring, etc. It's designed to facilitate management of your GNU/Linux boxes in Azure. The source is available if you want to compile it on something else.