As I found out recently when I was putting some of our son's newborn things away, breastmilk really is the gift that keeps on giving. In his first few months our son spit up a LOT - on himself, on us, on bibs, burp clothes, blankets, you get the picture. The stains seemed to wash out but now, nine months later, I was distressed to find prominent yellow stains on everything. After some panicked Googling, I found a solution...Apparently "protein stains" often don't appear right away so you can store things away clean and discover the stains much, much later. In my case the yellowish stains were most noticeable on whites. I tried laundering them normally which did nothing and then tried bleaching the whites which also had no effect. Finally I found some good information in Mamapedia on Mamasource (which, incidentally, we're finding lots of helpful advice on) via this thread. The majority of commenters had success using Oxiclean - see the post for more details and a few other strategies.
It's hard to tell from my photos, but after a long soak (overnight) in Oxiclean and sun exposure for an afternoon on the laundry line, most of the stains are gone (yee haw!). There are a few places on a few items that are still a bit yellowish, but it's a relief that almost all of our newborn things are restored to their former glory.
Anyone else care to weigh in with other solutions for this problem? Does formula cause the same kind of staining - if so, what's your best cleaning strategy?