Second choice of Iowa voters?

As a veteran of caucuses in Minnesota, I have been surprised that not much has been made of the results of the Zogby poll regarding voter's second choices.  

Final Zogby tracking numbers:

If the caucus were held today, for whom would you vote?
Kerry: 25%
Dean: 22%
Edwards: 21%
Gephardt: 18%

From the same list, who would be your second choice?

Kerry: 25%
Edwards: 21%
Gephardt: 15%
Dean: 13%

How do you think this will affect the outcome?

Also, does this tell us something about how undecided voters might view Dean?