It's a cool graphic, and very illustrative in itself. But I wanted to try to build on it a little by mappifying the data. Lax and Phillips looked at seven civil rights issues which are represented on the chart as same-sex marriage, 2nd parent adoption for same-sex couples, civil unions, health benefits for same-sex partners, job antidiscrimination, hate crimes protection, and housing antidiscrimination. The chart shows support for each of these for every state. The order I listed them in is generally the order of increasing popularity; for instance, same-sex marriage only has majority support in 6 states, but hate crimes protection and housing discrimination have support in all 50. So here is a map showing public support for gay rights policies:

It's the usual pattern: support for civil rights for gays is strongest in the Northeast, followed by the West, then the Midwest, and finally the South (and Utah).
But Lax and Phillips also include the actual status of those seven gay rights policies in each of the states, which creates quite a different looking map:

The trends are similar, but overall the map is just a whole lot paler, which is to say: public policies are lagging behind popular sentiment. I don't know whether this is because politicians tend to be behind the curve on gay rights issues, or because the legislative gears just need time to turn to catch up to public opinion, or what. But it does suggest there's a lot of room for gay rights legislation to advance in most states.
Here's one more way to look at it: the map below shows the number of Lax and Phillips' gay rights policies that have majority support but haven't been enacted.

The states in the Northeast, the West Coast, and the Upper Mississippi Valley don't just tend to have stronger support for gay civil rights - they've generally made more progress in legislating them. (Maine, Iowa, and Oregon have actually enacted more policies than have majority support.) But the biggest laggards aren't confined to the South; areas in the northern Interior West and the Rust Belt also tend to be behind the curve of presumed majority support (Alaska's the farthest behind, with support for five policies and none of them enacted).
It will be interesting to see how this map fills in over the coming years. I imagine we'll see consolidation for civil rights in areas outside the South first. And if the history of anti-miscegenation laws is prologue, it may take a Supreme Court decision to extend these rights throughout Dixie. Anti-miscegenation laws were obviously tied in to a very different history of discrimination; but nonetheless, if progress for gay rights were to follow a similar path, I wouldn't be surprised.