I'll have a crack as well. I reckon Perth will be on average down about 3-5 percent for the year. I don't really know the market in the rest of Oz. Whether it is correct or not the general perception is that Perth real estate is overpriced and sentiment is always a big factor in peoples decision making.
Can't see property crashing but i can see it doing nothing for quite a few years. Am willing to admit that i could be totally wrong though.