Download standard Linux source package here
then tar xzvf gmail-notify-188.8.131.52.tar.gz in the directory you downloaded Gmail Notifier to then go into the created directory with the files and start the notifier with ./notifier.py
Download a Debian package here
then dpkg -i gmail-notify-1.6.deb in the directory you downloaded to and type 'notifier' at an X Windows shell to start the notifier
Download a Windows installer here
then run the exe and follow through with the installer, during the install process, notifier.conf will be opened in notepad. You MUST edit this file to match your Gmail account
Note: The Windows version is currently broken and will not be able to check your Gmail account for mail. It will be fixed at a later date.
Gmail Notifier is freely distributed and licensed under the GPL