iPhone 3G users who updated their OS to OS3.0 will surely love this post. Ultrasn0w has been released for OS 3.0 running iPhone 3Gs.

Before you unlock your iPhone 3G, you must jailbreak it. Ultrasn0w  by iPhone dev team uses a payload which loads when you boot. It injects the payload at boot and also whenever there is a baseband reset. Which is quiet similar to what Redsn0w did. You won’t notice anything about it other than that all Networks now work. Once you have a Jailbreaked iPhone using redsn0w then you can use these easy stepsto Unlock.

Follow these steps:

1. Launch Cydia Installer, Select the Manage tab at the bottom of the screen, then click the Sources button

2 : Click Edit at the top right & then Press the Add button at the top left. Enter http://repo666.ultrasn0w.com/ in the source url and click the Add Source button. Now cydia would validate the supplied URL, check for updates in the source URL mentioned

3 : Once it has been added and updated, click the Return to Cydia button. Press the Done button at the top right of the screen.

4 : Touch to select http://repo666.ultrasn0w.com/ from the list of sources.

5 : Touch to select ultrasn0w from the list of packages.Press the Install button and confirm. After installation completes successfully press the large Return to Cydia button, restart iPhone.

Also, check out the video from iPhone dev team ;) . They rock!!