Two people, recently, have come out in support of civil marriage equality: former First Daughter Barbara Bush and current Maryland State Senator Allan Kittleman. Bush's direct ties to the former Presidents Bush have made her announcement newsworthy. It is important to note that she does not hold elective office, and because I've never heard where she falls politically, I think that her support of marriage equality is both great and representative of her generation (like Meghan McCain, who is a Republican), but not necessarily politically moving.
Kittleman on the other hand is a sitting Republican State Senator, and Maryland is in the process of actually considering marriage equality. He is planning to vote for marriage equality. That, in my mind, is even more important than joining a campaign (though it is a campaign I fully support). I was moved by his full statement that is published in this article in the Washington Post. I doubt that I agree with Kittleman on too many things politically, but I like to give credit where credit is due. And, I think that every straight Republican who is ambivalent about supporting marriage equality should consider reading Kittleman's statement.