Install wmctrl before running:
sudo apt-get install wmctrl
Change the desktop-indicator.py script to executable:
chmod +x desktop-indicator.pyAdd desktop-indicator.py to startup applications or double-click it in Nautilus and select run.
Show desktop indicator for Ubuntu Linux
So I was messing around with some Python code and I was able to cobble together a small app which puts a show desktop icon into the Ubuntu Unity panel. You can do the same thing with a hot corner in Compiz or press the Windows key plus D to show the desktop. Download the archive, extract the files and read the readme file for help.