The Gnome Gmail Notifier project aims to provide a stable, efficient GTK+2.0 application that provides periodic updates that pertain to the user's gmail inbox. The Notifier presents itself as a system tray icon in the GNOME2 desktop, displaying a small balloon popup when the user recieves new mail.
For more information, please see the About page in the wiki section, and check out http://notifier.geekysuavo.org/ for more detailed information, screenshots, and downloads of the GNOME Gmail Notifier.
If you want to stay updated on the gnome-gmail-notifier project's releases and fixes, you can subscribe to http://notifier.geekysuavo.org/feed.xml