Yesterday, Apple released the new Firmware Version, iOS 4.1 beta for developers.
It destroys the Ultrasn0w Unlock 0.93 with the new Baseband Baseband 05.14.01.
But the DevTeam found a breach on every firmware, so it's just a question of time until they will Unlock this Version.
iPhone 3G and iPhone 3GS should NOT upgrade if they want to unlock it later.