Bleasby made a good post on the other property thread.
I also posted the following hand waving reasons for a possible drop: - Prices are at record highs (and affordibility at record lows) - Slower economy and increased credit costs due to credit crisis - More stringent lending standards from banks - Low rental yield (even with record high rent) - Current pessimism in the media regarding house prices (report from IMF that 25% overvalued etc) - The "house prices never drop" myth has been busted by US/UK/NZ/Ireland etc all seeing large drops.
I couldn't give you an exact figure by which I expect prices to fall. It just seems silly to think that it is not possible, with all of the current turmoil.