FancyZoom, rewritten using Prototype
What that means exactly, is that Cabel's implementation retrieved the data for the "pop up" window the moment you clicked, whereas John's actually loads all of the "pop up" window's data that he needs on the initial page load. Obviously both of these methodologies have their place, their pros, and their cons, but it is all about choice, isn't it?
The one thing I do like about John's implementation over Cabel's is that it allows for just about anything to be loaded in the "pop up" window rather than only images. But this is only a small distinction in that Cabel's code could be easily modified to allow the very same thing.
Now, if someone would take the time to simply port this to jQuery so that I don't have to...
Source: FancyZoom meet Prototype.