Our club did a "Strange Brew" contest not long ago where we each drew "strange" ingredients (e.g., Jolly Rancher candies, marshmallow fluff, breakfast cereal, black pepper, licorice, oysters, etc.) from a hat, then had to make a beer with whatever ingredient we drew. The brewer who drew peanut butter found a powdered peanut butter product that was very low in oil. His beer had decent head retention. The peanut butter flavor was present, but not very strong.
FWIW, there were around 18 entries. 1st place was Robust Porter with Licorice, 2nd was Black Pepper IPA, and 3rd was Jolly Rancher American Wheat.