alt Hacker NewsAndroid still runs on a monolithic kernel written in a memory-unsafe language. I'm finding it suprisingly difficult to find information on Meadow, other than it runs .NET DLLs as user-space applications, but nothing about the structure of the kernel.
Longhorn was going to be more than that. Microsoft did have Singularity/Midori projects, started around the middle of Longhorn/Vista, and continued much longer after Vista released to build out the managed microkernel concept. It's been about a decade since they've put any work into it, though.
Microsoft wasn't even able to deliver that, which was my whole point.
Joe Duffy mentions on a talk, that even with Midori running production workloads, Windows team could not be changed their mind.
Meadow uses a C++ based microkernel, the whole userspace is based on .NET, by the way.