The latest version of Ubuntu is now available for download : Precise Pangolin. All of you that have the above version can install this new through Update Manager.
The main changes come at Unity, Canonical wanted to polish and improve the face of overall system usability. Have also been completely removed the default Mono libraries and especially the inclusion of HUD, a tool that has its roots in the famous Quicksilver OS X or other application launchers
like Launchy on Windows and allows us to perform some actions more common, both in terms of open applications such as to implement actions within them using only the keyboard.
We can apply a specific action, control the music, see your browser history, change our state of readiness in the messaging client Pangolin... is not a critical update for Ubuntu and doesn't brings drastic changes or, as in his day was the inclusion of Unity, but of course it is recommended if you use Oneiric Ocelot or any of the above.