Ubuntu 12.04 LTS Precise Pangolin beta 2 has been released on 29th Mar, 2012. You can download it from Ubuntu.com. It contains many new changes from its previous alpha and beta versions.
The main changes in Ubuntu 12.04 beta 2 are as follows. First is the HUD[head up display] animation. Then the updated version of Unity which is 5.8. Qt based Ubuntu One desktop client. Additional application quicklists. And the brand new multi-monitor option for LCD and projectors. Updated Firefox and Libreoffice packages and many more. The last version is Ubuntu 12.04 beta 1 which was released on 1st March, 2012.