Ubuntu is a Debian-based Linux operating system, with Unity as its default desktop environment. It is based on free software and named after the Southern African philosophy of ubuntu (literally, "human-ness"), which often is translated as "humanity towards others" or "the belief in a universal bond of sharing that connects all humanity". According to some metrics, Ubuntu is the most popular Linux distribution.
XFCE 4.10 has an Official Xubuntu PPA now!
sudo add-apt-repository ppa:xubuntu-dev/xfce-4.10
sudo apt-get update
if you have the XFCE 4.10-pre installed
sudo apt-get dist-upgrade
If you do not have it installed and want to install it
sudo apt-get install xfce4