It's Jack Newman's protocol for treating thrush. Nystatin has fallen out of favor because:
1) yeast are increasingly resistant to it and
2) it's administered in a sugar-based liquid, which would seem to feed the same yeast you're trying to kill.
It apparently has a pretty dismal success rate for these reasons.
So Gentian Violet is preferred over Nystatin.
However, some people find that Grape Seed Extract is also successful (and not purple-scary-weird). For the protocol for that, check Dr. Jay Gordon's site:
we used both gentian violet and grapefruit seed extract (for separate incidents of thrush) and we found the GSE worked better for us. from talking to friends who have also dealt with it, each person had success with a diiferent remedy.
also rinse EVERYTHING with a 1:1 solution of distilled water and white vinegar, your bras, burp cloths, toys, binkies (if you use them), even cloth dipes if babe has a yeasty rash.