Dilma is trouncing Serra and looks like winning straight on round one (that happens October 3rd, less than a month away now). Good.
The data for the poll was collected by Datafolha between September 2nd and 3rd. It was a big sample, with 4,314 people surveyed in 203 different municipalities up and down Brazil with a margin of error of +/- 2%. Data from here.
Go Dilma!