Ubuntu 11.10 with new changes is released with the code name Oneirk Ocelot. New changes are included in the unity interface of this 11.4 build.
Example: Window controllers on the top side are hidden now.Themes are also updated.Beta version of firefox 7 and Thunderbird 7 are included in the Beta version of Ubuntu.
Download link : http://releases.ubuntu.com/11.10/