How did I unlock?
1. Install iOS4 if not already done and sync your iPhone at least once with iTunes.
3. Slide the “Slide to Jailbreak” button
It will download few files, and start jailbreaking. This will also install Cydia app in your phone.
4. Open the Cydia app
5. Go to Manage tab, Click on Sources, Click on add button
6. Give the url http://repo666.ultrasn0w.com as source url, and download ultrasn0w.
7. Install the downloaded ultrasn0w; the phone will restart, and now UNLOCKED !
I just followed the detail steps given in Amit Bhawani’s blog post.