I've recorded a short, 10 minute screencast about presenters to give you a good view of what they are, where they came from and what they're good (and bad) at. It's illustrated with an example from our recent work on a loans processing application for the UK government.
Presenters allow you to create simple, understandable, self-contained objects. The screencast goes a little further than Jamis Buck's ‘skinny controller, fat model’ dictum to arrive at ‘skinny everything’.
With smart use of presenters, you can get some of the advantages of OOP without committing yourself to the downsides of enterprise Java.