Earlier today, Zibri - a member of the iPhone Elite Team - released a new jailbreak utility for iPhone firmware 1.1.3. This latest jailbreak is rumored to be the same method that the iPhone Dev Team has been guarding in anticipation of the iPhone SDK release - the "true" jailbreak (as some have termed it). Zibri's jailbreak utility, called ZiPhone, is said to have been created without the assistance of the iPhone Dev Team and as such was released without their cooperation/consent.
ZiPhone will apparently take care of jailbreaking and unlocking your iPhone running firmware version 1.1.3 without requiring you to downgrade to an earlier version of firmware. What's more , Zibri claims that ZiPhone can actually 'revive' many phones with dead basebands.
Both Mac OSX and Windows versions of ZiPhone are available and can be downloaded