The team with the advantage needs to use the extra man to put more pressure offensively. The Aussies have not been pressing the advantage until now. The risk is an Italian counter attack. I think the Aussies have the advantage in extra time. It is dangerous now for the Aussies.
If Italy can hold on through OT, with Buffon in goal, they should be favored in a shootout
"I think the Aussies have the advantage in extra time"
I agree. When Materazzi went, I still thought Italy would win. But if it does go to extra-time, you would expect the 10 men to be less up for it.