OpenNebula is a toolkit used to build private, public and hybrid cloud infrastructures. It has various advantages over other toolkit like Eucalyptus. OpenNebula is a light weight toolkit when compared to others. Following are the few specs which are supported by OpenNebula toolkit.
1.Hypervisor Support: KVM,Xen and Vmware.
2.Interface Support: Web based application/control panel, API and command line.
3.OS Compatibility: Ubuntu, SUSE, Linux, Solaris and Debian (supports both 32 and 64 bit).
4. Language support: Perl, PHP and Java.
Follow the link to the documentation given below to install OpenNebula using Ubuntu. Detailed instructions are provided by the author, i would rather say it spoon feeds you the instructions. How To Install OpenNebula Using Ubuntu