virtualbox

Install virtualbox 4.0 in ubuntu 10.10
Edit /etc/apt/sources.list file

  deb http://download.virtualbox.org/virtualbox/debian maverick contrib
Add gpg key

  wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -
Update source list

 sudo apt-get update

Install virtualbox 4.0

  sudo apt-get install virtualbox-4.0

may need:
sudo apt-get install dkms


from:
http://www.ubuntugeek.com/virtualbox-4-0-released-and-ubuntu-10-1010-049-10-installation-instructions-included.html