I recently saw this product in Youtube video on Makeup By RenRen's blog. She mentioned how it was great for removing stubborn stains from brushes. So, I decided to pink some up at Michael's (craft store) to try. All I can say is that Pink Soap is fabulous.
To use, I simply squeezed a small amount of the soap into the palm of my hand, swirled the end of my brush in the soap, and rinsed. It literally removed stains from my brushes that had been there for ages.
I definitely recommend it!
BEFORE (stained for months):
AFTER (all clean!):