Hey folks it is not been long since Apple released their iOS4.3b1 the new Firmware beta for the Developers. But the amazing thing is that the new Firmware iOS4.3 will not be for iPhone3G users. So they are on a safe side. The maximum firmware they can go is onto iOS4.2.1 which easily unlock able by the current Ultrasn0w. Even though @Musclenerd also Tweeted on his Twitter confirming that iOS4.3 is not for iPhone3G.
So if you are an iPhone3G owner and stuck on iOS4.1 or iOS4.2.1 so you can follow a complete guide here on how to Jailbreak your iPhone and update the baseband and unlock it using Ultrasn0w.