And, what do the polls show from August 1 - Sept 30?

There were 10 polls http://www.realclearpolitics.com/epolls/ 2008/president/ia/iowa_democratic_caucus -208.html#polls  

Three show Edwards ahead, one shows Obama ahead, and six show Clinton ahead. The RCP rolling average for the entire month of September is +3.5% for Clinton; and that number has grown throughout the month, the one poll with Obama ahead notwithstanding.

It's clear that Iowans are learning about Clinton from more than just visits. They are watching the debates and forums like everyone else.

BTW, Clinton will be spending a lot of time in Iowa this month.