From The iPhone Wiki
GuideMyJailbreak is a new jailbreak website that walks you through a few reasons to jailbreak, some misconceptions you may have, how to jailbreak, and how to use your new jailbroken device.
Re-Provisioning (Unlocking iPhone 4 (iPhone3,3))
- iPhone 4 from Verizon to other CDMA Carriers using OTA (Over The Air)
- iPhone 4 from Verizon to other CDMA Carriers using the file system
- Mounting the Ramdisk of IPSW in Betas 4-7
- Understanding iPhone Backup Files
- Change or Customize Date and Time Formats
- Creating a NOR-only IPSW
Check also the link section.