Is There a Jewish View on Same-Gender Marriage In the Public Sphere?

With the votes in Maine and Washington today, I saw some stuff on Twitter that made me think about it, especially Alan's tweet that says "Doesn't understand these anti-marriage-equality folks in DC: why do they think their (dumb) religion has say over CIVIL marriage? Jews don't."

This got me to thinking: is this so? Does Judaism believe that a same-gendered marriage may occur?
What makes this a not simple discussion begins with the following midrash, commenting on Lev. 18.3 (even though verses 2-5 are part of the introduction to verses 6-23, with verses 24-30 being the conclusion to the middle section), the rabbis treat verse 3 as referring to something not [necessarily] in verses 6-23 (Sifra 9.8):

כמעשה ארץ מצרים וכמעשה ארץ כנען לא תעשו, יכול לא יבנו בניינות ולא יטעו נטיעות כמותם תלמוד לומר ובחקותיהם לא תלכו, לא אמרתי אלא בחוקים החקוקים להם ולאבותיהם ולאבות אבותיהם ומה היו עושים האיש נושא לאיש והאשה לאשה, האיש נושא אשה ובתה והאשה ניסת לשנים לכך נאמר ובחקותיהם לא תלכו

"Like the actions of the land of Egypt or like the actions of the land of Canaan you shall not do" - Is it possible that [this means that] there shall not be built buildings nor shall there be planted plantings like them? What can be learned out from this passage is that "In their particular ways you shall not walk" - I would have only said 'in their particular ways which they have distinguished as being particular to them and to their fathers and to the fathers of their fathers.'

So what did they do [that was problematic that this verse is prohibiting]? A man would marry a man and a woman would marry a woman; a man would marry a woman and her daughter and a woman would be married to to men. Therefore, it is said, "In their particular ways you shall not walk."

If that were the end of the story, it could just be that these are things Jews, alone, are to avoid, while whether or not gentiles are to avoid them is unclear. However, what further complicates the matter is the notion of the 7 Noahide commandments, which, according to Jewish tradition, are to be followed by gentiles. One of these seven is widely known as Sexual Morality - included in this commandment are a number of sexual prohibitions, including incest, bestiality, and adultery, but also includes homosexual sex between two men (but not between two women).

However, if this sexual morality aspect were to include the prohibition on marriages mentioned in the midrash, then, according to Jewish tradition, not only for Jews is same-sex/gender marriage prohibited, but also for non-Jews. And, if Jews are supposed to be the light to the nations, then we shouldn't be helping the rest of the world in a direction that is not in their best interests. On the other hand, this discussion could only arise when Jews could be able to contribute to the conversation....