The latest iOS 4.3 SDK version was just released a few days ago. The change log mentioned that it comes with new baseband 4.08.00 for iPhone 4 and baseband 7.11.00 for iPad. iOS 4.3 and beyond will no longer support iPhone 3G.
For unlockers who do not mind using iPad’s baseband 6.15.00 which can be unlocked using ultrasn0w 1.2, you still have a few weeks left before Apple replaces it with version 7.11.00. The new baseband will definitely patch the vulnerability of version 6.15.00. If this happens, the only possible way to have 6.15.00 on your iPhone 3G or 3GS is by installing a custom firmware.
Meanwhile, @MuscleNerd from the iPhone Dev Team had confirmed that the unlock (most likely for iPhone 4) will not be released until iOS 4.2.5 or iOS 4.3 is out, whichever is last. If Apple did not fix the exploit found in basebands 2.10.04 and 3.10.01, then the new unlock will be able to unlock 3 different iPhone 4 basebands at the same time! So it does make sense for the Dev Team to hold the unlock.
Just be aware that by updating to the latest iOS blindly, you will risk of losing your jailbreak and for unlockers – you may lock up your iPhone for an extended period of time. For AT&T customers, you may have received a text message to update your iOS to 4.2.1 a few days ago! A slightly different tactic by AT&T to trick ultrasn0w unlockers!
Stay tuned and subscribe to us for updates! We will let you know as soon as the unlock is out. If you don’t see it here, that means it’s still not out. :)