I have an idea for an iphone App whereby a level of credit-based after sales service would be included in the initial purchase price.
This would be dependant on being able to verify that the person seeking to register for the credit could be verified as a paid up buyer of the application.
Is there currently any way to tie a person to a purchase? Do Apple supply email addresses of customers for example? If not how could this best be accomplished?
The only way so far would be to register upon first launch - however that won't help you when the app is pirated or re-installed.
There are ways of knowing if the app was paid for, but you'll still have problems with reinstalls.
So far, Apple doesn't disclose buyer information.
Since this more than likely involves Apple confidential information, you'd probably be best served asking it on the ADC Forums. Good search keywords might be "app purchase fraud".
You can make use of the new im-app purchase feature in OS 3.0. They can pirate the app but they will have to pay to unlock specific features.
What you want is to wait for the next version of the iPhone OS to release as Apple has already announced that it will allow for a tiered service structure, which is exactly what it seems you're talking about.
Also, for piracy issues, there is apparently a simple fix (I haven't gotten that far along yet) to compare the sizes of the compressed file, and apparently pirating an app requires a size change. When comparing you can choose not to load (block them entirely), or, as some developers have done, basically turn your game into a "demo" app and only load specific portions (i.e. let them try it out).