Ubuntu has released the latest version of it’s mainstay operating system, [version 12.04 “Precise Pangolin”] to the world. This has the third (and from everything I’ve read, greatly improved) version of the “Unity” user interface. This is also an LTS (Long Term Support) release which will be supported until April of 2017.
You can read the press releases for the desktop or server versions (neither of which mention the release by name interestingly), take a tour using their sweet web UI mockup of the distro or heck, just go and download it right now. Iloveubuntu.net has a review based on the final release.