I've not taken a look at the scripting yet to see if there is a way of scripting this, but imagine the following situation.
Being a good CAD user you are drawing an object (let's say... a plan of a plot of land and a building). Everything is effectively drawn at a scale of 1:1, although it'll never be printed as such. When you come to print, you have to include information about the diagram including the scale. You create a little box, add a drop shadow, put in some text saying "Scale: " and then realise that for all the work you've done to disconnect the drawing from physical media, you now have to tie yourself down to a scale.
At a simple level, my question is: Is there a way to tie some text on the page to the current plotting scale?
At a more complex level, is there a way of having an overlay (a sort of meta-layer) that can be scaled independantly of the plot (perhaps always plotted at 1:1). To expand on this a little: Imagine being able to print two images simultaneously. The first, lower, layer being the CAD drawing, the second, upper layer being the information. This second layer would remain at the same scale, while the first layer could be scaled according to the requirements of the plot. Certain bits of information (such as the scale) could be stored on the second layer as fields, to be updated automagically by QCad when actually plotting. It strikes me that plotting in this way is an inherent part of the life-cycle of a drawing and would benefit from explicit support.