bperrybap:
What I'm not sure of is how much the output pin droops. If it droops enough to be read as a LOW (which I'm assuming that it does given the "short")
With the base-emitter junction of a transistor pulling it down, it will droop, make no mistake! The technique would not be so useful to detect for example, being connected to the backlight LED with no series resistor.
bperrybap:
A better alternative to moving the resistor would be to replace the transistor with a FET like a 2n7000.
Presupposing you have a drawer full of surface-mount FETs. I do not, and being late at night, I did not feel like exhuming my SMD resistor stock from the garage either. XD
I asked Nick to make this a "sticky" as the matter is to my mind, just so important (with the clear risk of damage to MCU boards).