What is the compelling interest of the state?

With the recent passage of legislation in New York State recognizing homosexual "marriage," I am prompted to ponder what the role of the state is in regulating marriage. In ages past the argument was made that the state had an interest in the encouragement and fostering of families as the building block of society. As redefined in recent legislation marriage is itself divorced from the very concept of family.
In 1974, the Washington Court of Appeals ruled that, “The fact remains that marriage exists as a protected legal institution primarily because of societal values associated with the propagation of the human race.” (Singer v. Hara, 522 P.2d 1187, 1195) Indeed, this same purpose has been repeatedly cited in other court cases. But we are now living in a world in which a vast number of individuals seek to separate sex from procreation. Simply put, one large segment of the population seeks sex without children while, at the same time, another segment is seeking to have children without sex. What a world!
When a state recognizes a marriage, it bestows upon the couple certain benefits which are costly to both the state and other individuals. Collecting a deceased spouse’s social security, claiming an extra tax exemption for a spouse, and having the right to be covered under a spouse’s health insurance policy are just a few examples of the costly benefits associated with marriage. In a sense, a married couple receives a subsidy.
Absent the interest in promoting procreation and protecting the traditional family as the optimal environment for raising children, what is the compelling interest of the state in recognition of "marriage"?
The cynic in me predicts that the parties who will benefit most from this redefined institution are the divorce lawyers