Download
You can download sources or packages. For packages it is recommended to use repositories since this make upgrade process easier.
Sources:
Ubuntu Hardy/Intrepid/Jaunty (all versions) packages:
Ubuntu repository (Hardy/Intrepid/Jaunty)
You need to add the following line to your apt sources file (/etc/apt/sources.list)
deb http://le-web.org/repository stable main
and the GPG key information:
wget http://le-web.org/repository/le-web.key sudo apt-key add le-web.key
Then to install the the application for Gnome:
sudo apt-get update sudo apt-get install yadsync-common yadsync-gnome
Then to install the the application for KDE4:
sudo apt-get update sudo apt-get install yadsync-common yadsync-kde4