1. Download GPicSync from http://code.google.com/p/gpicsync/
2. Unpack it:
tar zxf Linux-GPicSync-0.91.tar.gz
3. Move to the directory it created:
cd Linux-GPicSync-0.91
4. Set the GUI and command line versions of the program executable:
chmod +x gpicsync-GUI.py gpicsync.py
5. Install the Ubuntu/Feisty package python-wxgtk2.8 which provides the python bindings for the wx library and the exiftool:
sudo apt-get install python-wxgtk2.8 libimage-exiftool-perl
6. Run the program and start geotagging photos:
./gpicsync-GUI.py