The situation in Spain is similar to the one in USA (both countries are hugely overbuilt with lots of unattractive speculative properties).
The decline started in USA in Summer 2006. At the beggining people did not want to accept reductions (except the peanuts 5%-10%). This was the denial period.
Then, at the beggining of 2007, when the spring sale season was a failure, started the
acceptance period with more drops.
California fell by 20% in one year, the unattractive areas lost 50%. Places in Florida lost
Now USA is in the panick period, when prices are falling like a rock (California loses about 5% per month, nobody knows when it is going to stop).
The factor which accelerates the fall in USA is the fact that people can mail back the keys to the banks when they are in negative equities (their credit is of course thrashed, but they manage to rent an apartment before their credit is destroyed).
If you are looking for bargains in Spain, have patience.
Out of the 35% off at PW, for the Brits 20% is lost due the loss of £ (as compared to 2007) and a 15% discount in a free-falling market is really a joke.