Umm, possibly. But I don't think that's quite what I had in mind...
I was thinking more along the lines that I could plug another (separate) Corona material node into the "distance from". Does that make sense?
At the risk of complicating things and side-tracking this thread; The example I can currently think of is that I sometimes 'fake' the window spacer in window frame materials. So I sometimes make a Corona Layered Material which has a distance map as it's mask, (referencing my window glass panes), so anytime the window frame material gets within X distance of the glass objects, the material changes from black metal (for example) to a silver-ish brushed metal.
Now, in this example, rather than referencing every poly object in my scene, I can reference the glass material into the "distance from".
Sorry to complicate things! But I hope this was a worthwhile explanation...