The New York Times says:

Mitt Romney, who is one of the wealthiest men ever to seek the presidency, said on Wednesday that he had no intention of releasing his tax returns if he became the Republican presidential nominee, breaking with a long tradition in both parties.

This is a big deal. First, it highlights Romney's rather egregious transparency issues. But it's also terrible election strategy: If Romney wants to hide his income from Americans, he's going to make his income the center of rabid press speculation. It's going to turn his fortune into even more of an issue than if he were to just release the returns and become the butt of a bunch of late night comedy routines about how wealthy he is. The facts behind Romney's money must be very damning, if he's willing to let the American imagination run amok about how huge—and how dirty—it is.