WinPwn 2.5 finally released to public for unclocking and jailbreaking your iPhone. Note that iPhone 3G cannot yet be unlocked by this tool and can only Jailbreak the phone. This tool supports up to firmware version 2.0.2.

Few notes from winpwn page.

- QuickPwn Support for 2.0/2.0.1/2.0.2
- Root partition resize support
- Installer support
- Basic / Expert modes
- Wizard style interface
- Automatic updater
- Support for WinXP and Vista 32/64bit.

You can download the tool here and please install and use at your own risk.