Do Ghasts spawn near portals in the overworld?

From the Minecraft Wiki

Notch added a small chance for Ghasts to spawn in the Overworld near Portals in Beta 1.5. A Ghast spawned outside of the Nether will fly everywhere, mainly above the clouds. Can even spawn extremely rarely without a portal.

Notch's actual confirmation

This is my understanding of the situation:

• Notch planned to have ghasts spawning near portals, before the Halloween update.
• It was not actually implemented in the Halloween update or any later one.

I believe the latter has been found to be the case by those who have studied the code of Minecraft, but I don't have a citation handy. Minecraft Forums would be the place to look for one.

they can't spawn in overworld, but they can get to overworld through portals if you built it 4x4 or bigger!!! .. making a security caution of building 4x4 nether portals so they can destroy your wooden house if they attacked you inside it.