Its confirmed now! There will be no iOS updates, unlocks, jailbreaks for iPhone 3G models. This is quite expected because Apple made it clear by not releasing iOS 4.3 Beta to iPhone 3G and iPod touch 2G models.
This has been also confirmed by MuscleNerd (iPhone Dev team hacker) that there will be no downgrade solution for users who have updated their iPhone 3G’s baseband to 6.15.00 in order to unlock.
His tweet –
Because there’s no 4.3 beta for iPhone3G, it’s effectively unlocked for life via the 06.15 ultrasn0w unlock
This means, iPhone 3G has been sticked to the iOS 4.2.1 update and it’s compatible jailbreak and unlock version. It is an unfortunate fact however, that this downgrade solution will not work for the iPhone 3G.