Capacitor Terminal Tin Whiskers

Picture the scene:

PSU - Transformer secondary connected to bridge rectifier connected to smoothing capacitor connected to load.
Question - what happens if a tin whisker grows between the smoothing capacitor positive and negative terminals, creating a short circuit.
Does the tin whisker, due to its miniscule size, simply act like a fuse and blow, which clears the short circuit?

Yes, I'd imagine that the whisker would blow, probably before you even noticed it.

I'm also inclined to suspect that if a transformer and bridge rectifier are required for the application, a tin-whisker short would most likely go unnoticed.

Low-power applications may be a different matter though.

Tin-whiskers can pass tens of mA in the right situations for growth:
NASA Goddard Tin Whisker Homepage