The Desktop Notifications framework provides a standard way of doing passive
pop-up notifications on the Linux desktop. These are designed to notify the
user of something without interrupting their work with a dialog box that they
must close. Passive popups can automatically disappear after a short period of
time.
The project homepage is located here:
https://edge.launchpad.net/notify-osd
This version of Notify OSD implements the specification defined here:
https://wiki.ubuntu.com/NotifyOSD?rev=143