On the Republican side, Sen. John McCain (R-Ariz) and former New York Mayor Rudi Juliani, trade measures, each grabbing the lead in two states.
Obama's high-profile apparently affects regular political consumers more than everyday voters. His lower-than-expected showing in some polls has been chalked up to lack of name recognition, but the voters in Iowa, South Carolina, New Hampshire certainly aren't political naifs, though Nevada has only recently begun to attract the attention the other three have.
That said, Obama's best performance in the American Research Group polls is in the state he has spent the most time in recently, New Hampshire.
Currently Clinton and Edwards are lying low. If Obama does decide to run, he could well make up any differential in name recognition with a year of steady campaigning. As a potential campaign wears on, his novelty will wear, but with careful planning he is guaranteed to have oodles of free press.