Dave Weigel writes this morning that Ron Paul's newsletters are "either a boutique issue that isn't connecting with people, a confusing issue that raises 'liberal media bias' hackles with conservatives, or both." That's based on comparing last week's PPP poll with the one released last night.
He could be right! On the other hand, as he says the newsletters were first back in the news in a Weekly Standard story late last week, which for normal people was probably swallowed completely by Christmas. They didn't really get a lot of traction until just the last couple of days -- while the poll was already in the field. And it's not clear to me to what extent those newsletters were brought to the attention of rank-and-file voters in Iowa, as opposed to die-hard political junkies.
To be fair: Iowa caucus attendees are hardly typical voters. They're more interested in politics, and far more likely to encounter this kind of stuff than are regular general election voters. But still: this sounds to me a little like all of the people who were claiming a week into the anti-Newt onslaught that he was immune to attacks for whatever reasons. It's very possible that it just will take a bit of time to sink in.