The latest version of NixOS can be downloaded from Softpedia
NixOS 14.04, a GNU/Linux operating system that is based on the Nix package manager, has been released and is now available for download.NixOS is not your average cup of tea, as it employs a rather different approach to the building of an operating system. It uses its own package manager, called Nix, which ensures that users can make an upgrade to one package that cannot break others, that they can always roll back to previous version, and so on.
“In NixOS, the entire operating system — the kernel, applications, system packages, configuration files, and so on — is built by the Nix package manager from a description in a purely functional build language. The fact that it’s purely functional essentially means that building a new configuration cannot overwrite previous configurations,” reads the official website.
The numbering used by the developer has nothing to do with the recently launched Ubuntu 14.04, and Canonical doesn't have a monopoly on the version type. In this case, it only notes the year and the month of the release.
According to the changelog, the installation on UEFI systems is now supported (this means that newer motherboards are also supported), Systemd has been updated to version 212 (the latest and best release so far), NixOS now automatically starts the system user instances when you log in, the operating systen is now based on Glibc 2.19 and GCC 4.8, and the default Linux kernel has been updated to 3.12.
This is not the latest Linux kernel available out there, but it's one of the best ones available, and it's likely that users will be able to download a newer version from the repositories.
Also, KDE SC has been updated to version 4.12, Nix has been updated to version 1.7, Adobe Flash player is no longer enabled by default in the Firefox and Chromium, and NixOS now supports fully declarative management of users and groups.
“If you set users.mutableUsers to false, then the contents of /etc/passwd and /etc/group will be congruent to your NixOS configuration. For instance, if you remove a user from users.extraUsers and run nixos-rebuild, the user account will cease to exist. Also, imperative commands for managing users and groups, such as useradd, are no longer available. If users.mutableUsers is true (the default), then behaviour is unchanged from NixOS 13.10,” also reads the release notes.
Check the official announcement for more details, new features, changes, and fixes. You can download NixOS 14.04 right now from Softpedia.