Check out this video if you are interested in learning how to Jailbreak AND Unlock the iPhone - Firmware 3.0.1 (August 2009).
Part One, JailBreak the iPhone:
1. On your Computer, Install "redsn0w"
2. Open the redsn0w application to jailbreak the iPhone
3. Click the Browse Button
4. locate the IPSW file and click Open
5. After seeing that the IPSW was successfully Identified, click Next
6. Check the "Install Cydia" Box and click Next
7. Plug the iPhone into the computer then turn it off. Then click Next
8. Place your device in DFU mode:
Hold Down the Power Button for 3 Seconds
Without releasing the Power button, also hold down the home for 10 Seconds
Without releasing the Home button, release the power button and hold for 30 Seconds.
9. Wait for your device to JailBreak and reboot. (if its stuck on waiting to reboot, unplug and reconnect the usb cable)
Part Two, Unlock the iPhone:
1. Open Cydia
2. Add "repo666.ultrasn0w.com" to your sources
3. Install "ultrasn0w"