Here is a step-by-step guide. Hope u guys find it useful.
Learn How-To Unlock the Galaxy Nexus Bootloader | Apple Umbrella
The steps outlined in the above link are useful but are not complete so I'm adding these supplemental instructions.
1.1 After you download the Android SDK go into the Tools folder and double click on the Android unix file. It'll open up the Android SDK Manager. Check all the boxes of everything that falls under Android 4.0 and click on Install packages (the button may be labeled "stall packages" if the window opened is too small because the letters get cutoff).
1.2 After you click on Install, another window should pop up with options to "accept" "reject" or "accept all". Click on "accept all" and then Install. It should take a while so go grab a sandwich or something.
2. So after the Android SDK Manager is done doing its thing you need to follow step 2 from the link above and download the Fastboot tool. After you download the Fastboot tool and unzip it, it needs to be put into the same folder that contains the ADB file. It should be under downloads/android-sdk-macosx/platform-tools folder, but make sure to double check.
3. Turn your phone off. Wait for about 5 seconds after it turns off then hold the volume button down (both up and down) as well as the power button until you feel the haptic feedback. It should turn on in bootloader mode and look like this
http://cdn.droid-life.com/wp-content/uploads/2011/12/nexus-bootloader1.jpg
4. It should read FASTBOOT MODE on top and LOCK STATE - LOCKED on the bottom. Although in that article it says "let any drivers install" it didn't do any of that for me so don't worry about that.
5. Now this is where this article kinda leaves you hanging and where I had to dig around a little to get it to work. Open your Finder and go to Macintosh HD/Applications/Utilities/Terminal. When you open terminal it should be a small white window (80 x 24) with black font. Type the following:
cd downloads then enter
cd android-sdk-macosx then enter
cd platform-tools then enter
./fastboot-mac oem unlock then enter
Your phone should go into this screen
http://cdn.droid-life.com/wp-content/uploads/2011/11/galaxy-nexus-bootloader.jpg
Move the cursor to Yes using the volume keys and click the power button to choose it. After you've done this it should unlock your bootloader and you can clearly see that it's unlocked when it takes you back to that bootloader screen from step 3 above. Now just reboot your phone and you're good to go.
Learn How-To Unlock the Galaxy Nexus Bootloader | Apple Umbrella
The steps outlined in the above link are useful but are not complete so I'm adding these supplemental instructions.
1.1 After you download the Android SDK go into the Tools folder and double click on the Android unix file. It'll open up the Android SDK Manager. Check all the boxes of everything that falls under Android 4.0 and click on Install packages (the button may be labeled "stall packages" if the window opened is too small because the letters get cutoff).
1.2 After you click on Install, another window should pop up with options to "accept" "reject" or "accept all". Click on "accept all" and then Install. It should take a while so go grab a sandwich or something.
2. So after the Android SDK Manager is done doing its thing you need to follow step 2 from the link above and download the Fastboot tool. After you download the Fastboot tool and unzip it, it needs to be put into the same folder that contains the ADB file. It should be under downloads/android-sdk-macosx/platform-tools folder, but make sure to double check.
3. Turn your phone off. Wait for about 5 seconds after it turns off then hold the volume button down (both up and down) as well as the power button until you feel the haptic feedback. It should turn on in bootloader mode and look like this
http://cdn.droid-life.com/wp-content/uploads/2011/12/nexus-bootloader1.jpg
4. It should read FASTBOOT MODE on top and LOCK STATE - LOCKED on the bottom. Although in that article it says "let any drivers install" it didn't do any of that for me so don't worry about that.
5. Now this is where this article kinda leaves you hanging and where I had to dig around a little to get it to work. Open your Finder and go to Macintosh HD/Applications/Utilities/Terminal. When you open terminal it should be a small white window (80 x 24) with black font. Type the following:
cd downloads then enter
cd android-sdk-macosx then enter
cd platform-tools then enter
./fastboot-mac oem unlock then enter
Your phone should go into this screen
http://cdn.droid-life.com/wp-content/uploads/2011/11/galaxy-nexus-bootloader.jpg
Move the cursor to Yes using the volume keys and click the power button to choose it. After you've done this it should unlock your bootloader and you can clearly see that it's unlocked when it takes you back to that bootloader screen from step 3 above. Now just reboot your phone and you're good to go.