Hi Ralphie.
It was in Recording Magazine January 2002, allegedly.
It keeps the 57's presence peak but damps some nasty resonances making it smoother. The SM57 was designed for transformers; the resistor makes the improvement on transformerless preamps. Ideally you calculate the value so the mic sees about 500 ohms, including preamp input.

No, I haven't actually tried it - the thing to do is put the R in a short M-F XLR cable and label it carefully!
One day, in my copious spare time...

Anahata