NixOS 16.03 “Emu” has been released, the fifth stable release branch. See the release notes for details. You can get NixOS 16.03 ISOs and VirtualBox appliances from the download page. For information on how to upgrade from older release branches to 16.03, check out the manual section on upgrading.
NixOS 16.03 released
Published on Sun May 01 2016