I too have noticed that a current batch of turbos just out of warranty (time, not miles) are selling for very little money. I personally think it's a combination of a couple of things:
• The recession is dragging on and for some, the garage toy must go to free up cash.
• Turbo owners who have not been affected by the recession want the PDK tranny in the new one and the new motor as well.
• When turbo 911's need work out of warranty, it's not cheap. Why dump that into an "old" car when you can sell it and buy a new one?
Of course, these are just my gut feelings. I could be all wrong.