From the ‘It’s April 1st, But This Is No Joke‘ files:
Ubuntu 11.04 aka – the Natty Narwhal is now available as a beta release. Why Ubuntu devs chose April 1st is beyond me, but rest assured this distro is no joke.
For starters Natty has the uber cool Linux 2.6.38 kernel, you know the one that makes everything faster. This will be the first of the big distros to include 2.6.38 and it will make the Natty experience for even current Ubuntu 10.10 users better.
For desktop users, the new Unity interface (think Gnome Shell, only better) is now
the default Ubuntu Desktop session. This is likely to be the biggest user experience issue that existing Ubuntu users will either like or dislike.
If you’re already a die-hard Fedora, openSUSE, Debian GNOME desktop user, this sort of change isn’t likely for you (then again you’re not running Ubuntu anyways for other reasons, so Unity is just one more reason..). Red Hat’s Fedora Project Leader at the time told me that he wasn’t worried about Unity and would be sticking with GNOME Shell.
Ubuntu announced back in October of 2010, that they would be moving to Unity, instead of GNOME 3 and the GNOME Shell approach. At the time of the Unity announcement, Mark Shuttleworth stressed that existing GNOME apps would still work in Unity.