Bobby's latest article named Using timeline labels to dispatch events with the ActionScript 3.0 TimelineWatcher class was published on Adobe Devnet and gives a comprehensive introductory on using Refunk's TimelineWatcher class.

The TimelineWatcher class enables a developer's code to watch a timeline as it is played back and be notified when a frame label or the end of the timeline has been reached. By using frame labels as hooks - cue points, as in web video - timelines and actions can now be truly separated from your application logic.

UPDATE
Thibault Imbert from ByteArray.org recently blogged about the FrameLabel event, a new feature request for the next version of Adobe Flash Player.