My thoughts on homosexual marriage aside (I'm undecided on a few issues, and I mean undecided before some take that the wrong way), I wonder why this issue hasn't been discussed much:
Divorce
Leaving aside the religious aspects involved in many marriages, the marriage contract is just that, a contract full of concrete ideas and implications for services rendered and provided. Divorce is fairly common in the Western world today and untold billions of dollars are spent each year in litigation and alimony/palimony payments. Furthermore, divorce laws involving children tend to weigh heavily in favor of maternal rights over paternal, even in cases of adopted children.
Now what is going to happen when the first gay divorces occur? I'm realistic enough to realize that homosexual unions will be just as prone to all the pitfalls of marriage as are heterosexual unions. But will this lead to a radical reinterpretation on how to divide benefits and children, since there aren't the easy biological differences to provide an out?
Should be an interesting next few decades watching this unfold 
Dylanfanatic 
Illusions fall like the husk of a fruit, one after another, and the fruit is experience. - Narrator, Sylvie
