I was asked yesterday if there was some way to set up a notification that new email had arrived using Google Apps Gmail.
Yes, Go download Google talk from http://www.google.com/talk and install it.
Once installed, if it doesn't open a Google Talk screen, double click on it down in the system tray by the clock in the lower left part of the screen.
You will need to login with your email address and password.
Once you've logged in, Click the settings link, Under the General Section, make sure "Start auto..." and "Open Gmail ...." are both checked.
Also click on the Notifications section on the left, and be sure "Show notification" is checked under the New Email section.
Click Ok and that is it.
You may also Click the X on the Google Talk window to close it and it will still be running and will have a popup notification when new mail arrives. You can tell it is logged in because the "talk bubble" looking icon will have a red M in it.