Ever wonder how that famous "Dewey Defeats Truman" headline appeared on the Chicago Tribune in 1948, held aloft by a smiling -- and victorious -- Harry Truman?

Polling technology, that's how. According to Craig Silverman's article on the subject, conventional wisdom, supported by polls, "was almost unanimous that a Dewey presidency was inevitable, and that the New York governor would win the election handily."

And how did the pollsters get it so wrong? They used the telephone to conduct their polls. Therefore they spoke with a disproportionate number of the relatively well-to-do, who could afford the technology. In other words, a cell phone poll would have predicted Democrat Martha Coakley defeating Republican Scott Brown for Ted Kennedy's old Senate seat in Massachusetts.

A recent piece in Salon noted that pollsters are now calling mobile phones. Telephones are ubiquitous in American society today, of course, so phone surveys are much more accurate. But calling cellphones raises many of the same problems pollsters had in 1948, as Salon notes:

"The cellphone-only demographic looks quite different from people with land lines: younger, poorer, more urban, less white and more Internet-savvy, according to a Centers for Disease Control study from last year." In other words, a reliably Democratic demographic.

The issue's kicking around because, as Salon notes, SurveyUSA, a robo-pollster, "has started making a move to include cellphones." Your more established pollsters that use live callers, like Gallup, use dual-mode calling. But pollsters using auto-dialers and recorded messages, such as Rasmussen Reports and SurveyUSA have only called land lines, which as Salon notes "has led to a lot of criticism of these pollsters, particularly when liberals want to try to debunk Rasmussen."

Such polls, however, might have stumbled upon a disquieting truth for Democrats: "These polls show an oddity: They find that the Republican candidates perform the strongest among the 18-34 set, despite exit polls consistently showing that that's the Democrats' strongest age bracket."

As Salon concludes, "This might mean that pollsters are better able to reach young voters but that their lack of enthusiasm means they don't fit the pollsters' screen for likely voters. Or it could mean there's been a sea change in the last year in the way young voters perceive the political parties. Neither of these possibilities is good for Democrats."