GNU Guix is a new free software project that aspires to be a package manager and associated free software distribution for the GNU system. The GNU Guix package manager offers features like transactional upgrades, rollbacks, unprivileged package management, per-user profiles, and garbage collection. Guix in turn is based upon the Nix package manager from NixOS.
A user-land free software distribution for GNU/Linux is part of Guix. The Guix OS isn't yet a bootable distribution but rather something that can be installed atop a currently installed GNU/Linux operating system. Guix is GPLv3 licensed.
The Guix project is currently approaching its first alpha release and was formally announced last week on one of the GNU mailing lists.
More information on Guix is available from its GNU.org project site.