When I stumbled upon the news story regarding the disappointing decision about the same-sex marriages Mayor West had performed in New Paltz, NY, I also found a great intereactive guide hosted by CBS News
In the box at left, they offer a pop-up, easy-to-use interactive guide, entitled "Same-Sex Marriage Debate," which offers "state-by-state coverage, opinions, history, photos and a look at the amendment process."
At TwoBrides.com & TwoGrooms.com, we frequently receive questions about where gay marriage is legal. Generally, these questions come from brides and grooms looking to get married. Hopefully, though, more prospective brides and grooms will do research like this so as to be proactively involved in the legislative process. Either way, one can visit this CBS Guide and click each state of interest to find out what the latest developments have been.
I also recommend HRC's online guide, featuring state by state overview and developments.
For those who just can't get enough, the CBS site also offers a resource guide called "Gay in the U.S.A.," which includes "state-by-state laws on gay issues, the marriage debate and photo essays."