Q: I know that the first cup of wine is the "cup of blessing" and that the third cup of wine is the "cup of redemption". What do the other two mean?
A: At the beginning of the Torah portion Va'eira, four expressions are used with regard to the redemption from Egypt: "I will release you... I will save you... I will liberate you... I will take you...." Our Sages note that the four cups of wine which we drink during the Passover Seder correspond to these four expressions. for whole article http://www.chabad.org/holidays/passover/pesach.asp?AID=1813