The 78th General Convention of the Episcopal Church authorized two new marriage liturgies that can be used for all couples, gay and straigt as well as a blessing liturgy to be used in countries where same-sex marriage is not yet legal.
You can find the rites in this Word document.
The document contains three liturgies. The Witness and Blessing of a Lifelong Covenant is the blessing rite.
The Witness and Blessing of a Marriage is a newer rite based on the blessing rite approved in 2012.
The Celebration and Blessing of a Marriage (2) is based on the traditional rite found in the 1979 Book of Common Prayer.
Church Publishing has just published the new rites and other materials in this book: "LITURGICAL RESOURCES 1, REVISED AND EXPANDED."
From the Task Force on the Study of Marriage
From the Standing Commission on Liturgy and Music
WHAT ABOUT THE BIBLE?
Video from my lecture "Jesus and the Gays"
GENERAL CONVENTION RESOLUTIONS
VIDEO OF GENERAL CONVENTION DEBATE