Ubuntu Natty Narwhal is now available for download.
Ubuntu Linux, easily one of the most popular Linux distributions available today, is out with what may be its most significant set of changes to date. 11.04 "Natty Narwhal" has brought with it not just major version jumps for nearly every core app and service, but also a completely revamped Unity interface.
Ubuntu 11.04 is also available in several variants, including the KDE-based Kubuntu, lighter-weight Xubuntu, Edubuntu, and more. These derivatives allow users to have all the updated features of the underlying OS while using the interface of their choosing, like KDE or XFCE.
http://www.ubuntu.com/