This is just a quick tip for anyone using another theme than the Human theme on Jaunty. Without the Human theme you'll get a translucent black box when notifications pop up, because the icons are aren't included in any other themes yet. Simply by appending Human to your theme's inheritance in index.theme:
That way you won't have to keep re-copying the icons every time the art team updates the human-icon-theme package.
Thanks to pferraro from the Ubuntuforum for this tip.