"I don't like O'Malley and I am no Dumbocrat / Caligulite. Still, methinks you should validate stuff like this before you post it." So wrote "Sartorius" on Aug. 13, 2004. The participant in a discussion board on FreeRepublic.com was responding to an explosive posting that Baltimore Mayor Martin O'Malley was having an extramarital affair. It turns out that even Web posters themselves question the publishing power the Internet grants anyone with a modem. Sartorius's skepticism proved salient: Another person posting about the topic was revealed this week to be Joseph Steffen, a longtime political operative for O'Malley's political rival, Gov....