Developer Zibri has posted a package for both Mac OS X and Windows that claims to jailbreak, activate and unlock all iPhones running software/firmware 1.1.3 (including out-of-the-box [OTB]) devices. The package uses the "true" jailbreak method that the iPhone dev team was attempting to keep secret until the release of Apple's official SDK rather than the previously divulged "soft-upgrade" method. Jailbreaking provides read/write iPhone filesystem access, allowing installation of unofficial third-party applications.
The jailbreak method includes incomplete instructions, however. Here's what you need to do to make it work:
[UPDATE: See our Applications page for full jailbreak instructions]
Note that some users are still experiencing problems jailbreaking with this package, and that this package was released without the consent of the iPhone dev team who has been refining the method and attempting to keep it secret until the release of Apple's iPhone SDK.
If this method fails for you, see our Applications page for full instructions on jailbreaking all firmware/software revisions.