Why not try and implement some anti-crack feature like the makers of BeeJive do? Then you won't have people stealing your app(s) AND you'll also save money by not having to buy boxes of tissues to wipe away your tears.![]()
If you read on Hackulous forums, you'll find that the hackers just LOVE it when developers spend time on DRM. Many do it for a hobby and see it as a "game" more interesting than the app itself.
iPhone app piracy is just a testament to how well the appstore is doing. I will tell you that middle income families with cash are not bothering to do the whole jailbreak->appsync->download process. It's just poor teenagers and college students who wouldn't buy the app anyway. Consider it free advertising.
Any developer that whines about piracy never has proof on how it is truly hurting them.