Yeah, I'd considered that too, but was just hoping to find something that would be even quicker.
That is, I'd just select an area on a full-resolution image, click a button and the plug-in would copy the selected area into a new layer, shrink the main image underneath it, and add some kind of transition / call-out effect between them. Maybe with a parameter or two to specify the distance and direction of the call-out from its original position in the thumbnail.
BTW, nice effect in your example.
Mal.