Well if Australia qualify for the World Cup wouldn't our ranking go up?
A little, but we are really held back by the fact that the asian confederation is ranked so poorly, so at the moment we're not really much of a chance to climb above rank 30. The problem was the last world cup, we didn't count as an Asian rep, and the other four didn't make it out of the group stage, which really dented Asia's standing. It means that a competitive result against an Asian nation isn't worth as much points as say a competitive result against a Euro nation or even African nation.
You also witnessed this with Concacaf; recall before the last world cup how mexico/usa were always mainstays of the top ten? Concacaf rankings were a little over-inflated, but a poor showing at '06 suddenly sent them tumbling down a bit.
And the tournament as a whole was dominated by the Europeans, so now we see middle-tier Euro sides with over-inflated rankings (although a european might argue this was merely re-dressing the fallacious results of 02 where Europe faired really badly). It's why Scotland is so high (16!!!), probably almost entirely by virtue of its two wins over France in Euro qualifying.
So yeah, it's performance at the World Cup itself which really dictates a team's ranking (both individual and as a confederation) because it's the only real means of comparing all the confederations.
Imagine this at 2010: No African sides get out of the group stages, Japan make the quarter-finals, along with Brazil, Argentina, four Euro sides, and Australia, who go on to lift the trophy. Afterwards, Australia would probably leap to about 5th in the world, sides like Japan, Iran, Saudi Arabia and South Korea would suddenly find themselves ranked in the teens, and the best african sides would be no higher than where you witness the top asian sides right now.
