The iPhone Dev Team released updated jailbreak tools for iOS 4.3.3 today. Ultrasn0w 1.2.3 was also updated for iOS 4.3.3. This is NOT a new unlock.
ultrasn0w has been updated to v1.2.3 to be compatible with iOS 4.3.3 and earlier (the ultrasn0w update does not include any new baseband support!). Please reboot your iPhone using the normal â€œslide to power offâ€ swipe after installing ultrasn0w 1.2.3.
Follow our ultrasn0w 1.2.3 unlock tutorial here.