..well hopefully for you Kazunori Yamauchi is not joking around and will give you a reason to pick up your copy of GT5P this fall again:
Earlier in the year, Polyphony Digital founder Kazunori Yamauchi (now of GT:TV fame, Top Gear next) mentioned that “maybe by Fall we’ll be able to implement it [ie. damage modeling],” and confirming that it would be included as a patch to Gran Turismo 5 Prologue. Their plans haven’t changed.
In an E3 interview with IGN, Kazunori reiterates that they are still working on implementing damage, but joking saying that, being Gran Turismo, “it might be a little bit late.”
The PD team are certainly perfectionists and this fact could reflect on the full release of Gran Turismo 5, which Kazunori says could come as late as 2010;
Of course after this next update, we’re going to have another update later on in the year. There’s no plans in the works for GT5 yet - that might be 2009, or it might be 2010… But we’re totally focused on getting the updates through for Gran Turismo 5 Prologue, and that’s all we’re focused on.
http://www.ripten.com/2008/07/18/gt5p-damage-modeling-still-in-the-works/