notify-sharp is a C# client implementation for Desktop Notifications,
i.e. notification-daemon. It is inspired by the libnotify API.

Desktop Notifications provide 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.

http://trac.galago-project.org/wiki/DesktopNotifications

