One of the things I missed when I said goodbye to Redmond's OS was the GTray notifier, but surely enough, apps of such ilk have already been created!

KDE (3.2.x) users can try KCheckGmail [http://www.kde-apps.org/content/show.php?content=14927] and
GNOME users can use GNOME GTray [http://www.kde-apps.org/content/show.php?content=14927].

There's nothing to stop you using the GNOME GTray in KDE, says the Website, but faithful KDE users in the war between the *nix desktop managers will feel more at home with something that starts with a trademark 'K', I feel. :)

Also, OSX users don't have to miss out either, there's a Mac clone of such an app at http://homepage.mac.com/carsten.guenther/GmailStatus/. Never have the charms of leaving Windows behind been so clear. ;)

Oops. GNOME GTray is at http://fraggle.alkali.org/projects/gtray/. :)