Remember my mishap with bleeding taffeta?
UPDATE (7/8/12): Today I finally finished ripping out the seams and removing the red lining of the vest and cape. I hand washed the white components with a bar of fels-naptha and then tossed them into the wash (cold water, medium cycle).
Result? IT WORKED! The costume is white again! (Ok there are a couple tiny pink stains, but I had to stare at the costume for about 5 minutes before I saw them all.) I doubt the casual observe will notice. And if they do…well I challenge them to point it out (see, I’ll be dressing as one of Ezio’s assassin apprentices).
A friend sent me information on colorfasting fabrics. I’ll be sending the taffeta through this process, but I won’t reuse it for Ezio. (I’m thinking maybe a “Number 6” red dress from Battlestar Galactica down the line.) I will look for another red fabric that is less likely to rub off (and colorfast it anyway).
PAX is just under 2 months away. QUICK, hurry, sew!
The Fabric Alchemist 
Glad your efforts worked! I recently had luck with a product called Vintage Textile Wash in restoring an old flannel from used-to-be-white-but-is-now-brown to its original sparkling white.