It’s April, the fourth month of the year, and that means it’s time for a new Ubuntu release. (This also true of the tenth month of the year — those Canonical folks like to keep busy.) Ubuntu 11.04, or Natty Narwhal as the kids are calling it, is here and packing some significant changes from earlier editions of the Linux distro. The most obvious being the arrival of the Unity desktop environment, which was previously relegated to netbooks. It's got integrated search, a combination launcher and taskbar, and app menus that have been moved to the top of the screen