Ubuntu Geek shows you how to install VirtualBox 4.1.4 on Ubuntu 11.04 and 10.10
Oracle VM VirtualBox, formerly Sun xVM VirtualBox and innotek VirtualBox, is a family of x86 virtualization products for enterprise and home use.VirtualBox is a general-purpose full virtualizer for x86 hardware, targeted at server, desktop and embedded use.VirtualBox 4.1.4 Ubuntu 11.04/10.10 installation instructions