It makes everything else, even the window manager, think the screen's height is N pixels less than it actually is. Then uses this free space for a ticker bar. It might be the window manager's work, actually.
The feel of it would be similar to KDE's knewsticker. Namely, horizontal scrolling, with clickable headlines that bring up your configured browser (opening a new tab in Firefox in my case).
Since I'm using WindowMaker, I'd want a bar at the top of the screen, as high as one dock tile (64 pixels, usually). That would hold 2 lines of text, so... even more information for this info junkie :)