Brookings Institution scholar (and frequent Reason contributor) Jonathan Rauch argues yes in an essay at The New Republic:
When he first campaigned for the White House, Barack Obama vowed to be a fierce advocate for gay rights, but it hasn't always been clear if he intended to keep his promise. Indeed, we gay folks had gotten used to grousing about the President. We noticed the way he dragged his feet after promising to repeal the ban on military service; we felt betrayed when his Justice Department insisted, as George W. Bush's had done, that gays have marriage equality already, because we can already marry someone of the opposite sex.
To gay Americans, this did not look like the fierce urgency of now. It looked like more of the same, what gay activists had come to expect from Democratic politicians: Do as little as you can get by with to keep the gay lobby quiet, but save political capital for more important causes and constituencies.
But it's now clear that the Obama administration has quietly accumulated an impressive and unprecedented record on gay rights. Indeed, with his health-care reform bill in jeopardy of being overturned by the Supreme Court or repealed by a future Congress, there's a real possibility that his efforts for gay equality will prove to be his most enduring legacy. The history books may remember Obama for doing for gays what Lyndon Johnson did for African Americans: Leading his party across a bridge to an irrevocable position on civil rights.