wget -q "http://deb.playonlinux.com/public.gpg" -O - | sudo apt-key add -
sudo wget http://deb.playonlinux.com/playonlinux_maverick.list -O /etc/apt/sources.list.d/playonlinux.list
sudo apt-get update
sudo apt-get install playonlinux
If you already did, running
sudo apt-get update && sudo apt-get upgrade should install the latest version.You can find the above code for your current version (for future reference) on the following link:http://www.playonlinux.com/en/download.html