As promised here is the iPhone 4 unlock now out officially. You can unlock the iPhone 4 with the latest version of Ultrasn0w. Here is a simple guide to unlocking your iPhone 4 on baseband 01.59.
1. Jailbreak your iPhone using the Jailbreakme hack
2. Add http://repo666.ultrasn0w.com to Cydia sources (its ultrasn0w with a ‘zero’ and now letter o)
3. Search for Ultrasn0w (again the 0 is a zero) and install it.
Thats it your are done!
Do let us know how this worked for you.