Bill Clinton got a hard lesson recently in a new rule of politics. Sen. Barack Obama (D-IL), meanwhile, tried to make some new rules of his own.

A blogger for the Huffington Post caught up to Clinton after a political event and, without mentioning her affiliation, prompted Clinton into a fiery denunciation of a Vanity Fair writer who'd written an unfriendly article about the former president. The exchange was recorded and made major waves.

The blogger's failure to identify herself as a ...