The court rulings and legislation which allow same sex marriages in those states do not, however, require religious organizations to recognize same-sex marriages or perform the ceremonies as all religions have the right to establish their own requirements for what constitutes a religious marriage.
States that allow same sex marriages have simply established the right to marry under civil law. This marriage can be performed by a Justice of the Peace, Judge or other civil official depending on state law. That said, there are a number of churches that have opened their arms to the gay community and are performing traditional weddings in the church for same sex couples. A marriage performed by such a clergy member would be considered legal as well.
See The Complete Guide to Gay and Lesbian Weddings for more information on same sex wedding ceremonies.