Using the Google Chrome browser you can install this extension (https://chrome.google.com/extensions/detail/kkmbodalobogbnejmcdghkfimhodifol) and it will auto-notify you with a small preview of the new email in the lower right corner of your screen, right away – No matter what you're doing on your PC. (As long as you're logged in to Gmail in Google Chrome.)

Or you can install this extension if you don't want the icon in your Chrome browser bar: https://chrome.google.com/extensions/detail/pdjhkgkojjmdfklngelklpcahdfbgiim

https://chrome.google.com/extensions/img/kkmbodalobogbnejmcdghkfimhodifol/1266152729.8/screenshot_big/1

http://blog.chromium.org/2010/05/desktop-notifications-now-available-to.html

Are the notifications able to display full html(5)? And interact with the user?