In the past on Phoronix we have mentioned ToaruOS a few times. It's a "hobby" kernel and operating system written mostly from scratch yet supports Mesa, GCC, Python, and more. It's been in development since 2011 while now the operating system's 1.0 release finally took place.
 

The ToaruOS developer wrote in about the Toaru 1.0 release that took place at the end of January. He wrote, "After six years of development, I am very happy to finally announce the 1.0 release of ToaruOS. While I would not consider this "complete" - there is still much work to be done - it is time to refocus my development, and with that comes the time to declare a stable release. ToaruOS 1.0 has been the result of over half a decade of effort, with contributions from a dozen people besides myself."
 

ToaruOS 1.0 can be run from VirtualBox or QEMU for easy hardware support. Currently it supports 32-bit non-SMP systems, a Unix-like environment, EXT2 file-system support, support for many Unix utilities, and many open-source software packages ported over like Vim, Binutils, SDL, Quake, Bochs, and others with its own package manager.
 

Since the Toaru OS 1.0 release two weeks ago there was a 1.0.1 point release with a few bug fixes and then this past week was v1.0.2 with audio improvements.
 

The project is hosted on GitHub and ISOs are available for easy testing. The project describes itself on GitHub as "Hobby kernel + userspace, built mostly from scratch. Composited GUI, dynamically linked ELF binaries, networking, Python applications, and more."