Those who like the design of the iPhone but not appreciative of Apple's walled garden approach rely on jailbreaking for freedom. Through jailbreaking, the user can both install apps that Apple doesn't approve of, as well as customize the look and even functionality of the iPhone.
Thankfully, this 'hole' has still been kept open for the iPhone 4. Just a few days after release, hackers have jailbroken the iPhone 4 using the Spirit jailbreak. Sadly, this exploit isn't ready for release as the developers say that it uses some of Apple's proprietary code.
The real takeaway from the report from Redmond Pie is that a jailbreak is certainly possible, so customization will live on for another generation.