Third alpha for Ubuntu 11.04, code named “Natty Narwhal”, is the last of three planned alpha releases. Unity is the new default desktop developed in-house by Canonical, replacing the GNOME Shell and replacing the OpenOffice.org office suite with the LibreOffice community fork. Other changes include updates to the Ubuntu installer allowing users to upgrade their existing Ubuntu installation to the new version, improved iPhone support and a new Ubuntu One Control Panel. The final version of the alpha is expected to arrive on 28 April 2011. The latest stable release is version 10.10 “Maverick Meerkat”
Source: https://thehackernews.com/2011/03/canonical-releases-ubuntu-1104-alpha-3.html