The Road to KDE 4: Job Progress Reimagined (KDE.News)
Picture it as a cross between the Firefox download manager and the KDE printer queue, except that there is no real restriction on what type of jobs can be monitored. The way it works is that each KDE 4 app that has a progress dialog adds a flag for something called an Observer. Then, a separate application can observe any running Jobs, displaying progress and even adding certain actions (like 'Cancel Download') which can be submitted back to the application that actually has the progress dialog."
