From USA Today:

Her husband has finally quit smoking, the first family does have a church and spiritual life, she's not revealing her position on gay marriage, and she and her husband keep their marriage strong with laughter.

First lady Michelle Obama answered questions Tuesday during an hour-long lunch with a dozen reporters... Her position on gay marriage? "I'm not getting into that."

I'm guessing that Michelle Obama will reveal her position on gay marriage sometime in late January 2013 or late January 2017, depending—you know, right around the time when her position won't matter much anymore.