Some information from S&F concerning harpoons:
If the attack is succesfull the harpoon may lodge in the victim if the victim fails a Reflex saving throw against a DC equal to 10 + the damage inflicted. The harpooned creature moves at only half speed and cannot charge or run. If I control the rope by succeding at an opposed Strength check the harpooned creature may only move within the limits that the rope allows. (I stated that I would tie the rope around me so that the harpoon could not be moved further away from me than 5', but Macbrea declared that the harpoon cannot be wielded if it is tied this close, allowing Garion to get 10' away.) If the harpooned creature attempts to cast a spell it must succed at a Concentration check (DC 15) or fail, losing the spell.
The harpooned creature can pull the harpoon from its wound if it has two free hands by taking a full round action to do so, but in so doing inflicts damage on itself equal to the initial damage the hapoon caused.
Macbrea ruled that ripping out a harpoon will not cause AoO.
"I," grins the ratman wickedly "am Kanyano the Killer!"