I'm really glad this video worked (watch it here). We shot it live as I ran ZiPhone, with fingers firmly crossed. Getting all the third-party applications back on my iPhone, is like getting a new phone. Here's what I did.
Apple has their own system for putting third-party applications on your iPhone, but Apple has to approve of the applications, meaning some stuff isn't going to be available.
The practice of unlocking your phone to third-party applications is often referred to as jailbreaking.