The draw kept Roma in first place with ten points while Juve stayed sixth with seven points.
Iaquinta ghosted in front his marker at the near post to connect with a long throw-in and send a lofted header past the Roma keeper with his back to the goal.
Juventus initially took the lead in the 17th minute when David Trezeguet connected with a fine cross to head home.
But two goals from Francesco Totti in the space of six minutes gave Roma the advantage before the end of the first-half.
The Roma captain rounded a challenger before slotting the ball past Juventus keeper Gianluigi Buffon in the 30th minute before tucking home on the rebound for the second goal.
Alessandro Del Piero slammed a penalty-kick over the bar three minutes into the second half after Pavel Nedved was brought down inside the area.