I have had an iPhone for about 2 years now, and I am still happy with my hacked / jailbroken 1st gen phone. I am what, amongst my friends, can be considered a computer geek. I can fix computers and code quite a bit, I have hacked my iPhone several times (upgrading from os 1-2-3) and I have no problem pirating games. Still, I have never pirated anything on the iPhone. And yes, I have pirated PC games.
The app store is just too easy and affordable. I buy about 2-4 apps, totalling about $5, per month. This is about equivalent to half a pint of beer here in Norway. I feel I get good value, I compensate developers and I dont get the hassle of hacking. And yes, I consider any kind of manually moving files on my computer and syncing with iTunes a hassle compared to clicking on the app twice on appstore.
I have about 20 friends with iPhone. Out of them about 1 has Cydia installed and maybe a couple would consider pirating. For most people the iPhone represents ease of use, and they dont wanna hack and figure out stuff. I see people all over with the iPhone, and the majority is not the hacking type. Of course it matters what age group and income level we are at, but I still think only a minor percentage of iPhone owners even have Cydia installed. The only number I have seen for is that less than 10% of all iPhones are even jailbroken.
So my point: From this personal annecdotal experience, I claim with confidence that at most 5-10 percent of the Apple iPhone owners have ever pirated an iPhone app. The numbers can be discussed, but the major part of the app market buy their apps.
Then the specific cases can be evaluated. Why is this app pirated so much? Does it appeal to geeks, has it been marketed better in the "pirating" community? Does the pirates download and use / try more sw because its "free"? Are people that upload highscores more likely to be geeks that have hacked iPhones? Are disproportionally more people who have hacked phones living in countries with lower GDP because the iPhone hasnt been sold there before, and they are therefore less likely to pay for apps because they have less money? These and many more are interesting questions, but I still believe that most potential users of iPhone apps does not even consider pirating.