At 13,OCT 2011 Ubuntu 11.10 named "Oneiric Ocelot" has been released. It comes with unity. It available on both 32 and 64 bit. This version contain many new features. Here in this article you can find that how to install Ubuntu 11.10 on virtualbox.
In this video, you learn the installation step by step like how much RAM is required, how much memory should given to it, from where you can select the .iso image and how to install it. Here we use Ubuntu 10.10 as the host OS.