Now when Nexus one already got the Android 2.2, Froyo just after the Google IO. It didn’t took too long to get the New Nexus One, Rooted again! 
I would like to write a easy step by step guide to root your Nexus One with detailed steps and screenshots to make it even more easier for you. Let me know if you find yourself stuck somewhere.
If you are wondering, why should i root my Android Device, you should perhaps have a look here, where i’ve explained it for Xperia X10 but it goes the same for any android device, including Nexus One.
But before i continue, let me warn you that Rooting and Flashing your Nexus one is a highly risky process and you should take responsibility of what you do to your phone. So, I would like to suggest you that before you continue further with the rooting of Nexus One with Froyo, Please read the steps carefully and understand them. And if you are unsure about any step, please ask me through comments.
Above statement was not to discourage you but it’s highly important to remind you that you need to be extra-careful while rooting your Nexus One with Android 2.2,Froyo!
You’ll Need :
————————————————
- Android 2.2, Froyo on your Nexus One
- Android SDK Installed on your Computer
- Recovery 1.7.0 for your Nexus One
- Froyo Rooter-Signed
Steps to Root Nexus One with Android 2.2,Froyo :
——————————————————–
The steps to root your Nexus one could be broadly divided into three main steps :
– Unlocking Boot Loader on Nexus One
– Installing of Recovery on your Nexus One
– Flashing the Froyo Rooter Signed Zip File
Step 1 : Unlock Boot Loader on your Nexus One :
——————————————————————
In order to Flash the Recovery Image on the Nexus One, we first need to Unlock the Boot Loader. Unlocking the Boot Loader might Wipe all your data on the Nexus One. So, it is strongly recommended to backup your Data using Backup apps for your Nexus One Phone. Here are some Recommendations for BackUp Apps for your Android Nexus One.
- Turn off your Nexus One and Reboot into Fastboot Mode ( Press Trackball + Power Button Simultaneously for 2-3 Secs ). The fastboot screen is the one with the Androids on skateboards.
- Open a command prompt and navigate to your Android SDK tools folder.
- Type “fastboot devices” to make sure your phone is recognized. If it is not recognized, you need to install the ADB Drivers for your Nexus One.
- Type “fastboot oem unlock” to unlock the bootloader on your Nexus One.
- Use the Volume Keys to navigate to “yes” and press the Power Button to confirm the action. It will Unlock your BootLoader on your Nexus One.
Step 2 : Install Recovery 1.7.0 on your Nexus One
——————————————————————–
Download the Recovery 1.7.0 for your Nexus One to be able to Flash the Foroyo Rooter on the Nexus One. It will also allow to Flash other custom Zip Packages from the SD Card.
- Copy the Recovery 1.7.0 that you just downloaded, into the “Tools” directory of the Android SDK. ( It should be in C:\android-sdk-windows\tools\ )
- Start the Nexus One in FlashBoot Mode ( Press Trackball + Power Button Simultaneously for 2-3 Secs ) again.
- Now go to the Tools Folder through Command Prompt or cmd in your Computer. ( C:\android-sdk-windows\tools\ )
- Type “fastboot devices” to make sure your phone is recognized. If it is not recognized, you need to install the ADB Drivers for your Nexus One.
- Type “fastboot flash recovery recovery-RA-Nexus-v1.7.0.img” to unlock the bootloader on your Nexus One. ( Please do not rename or unzip any file you download. )
- Above command will successfully Flash the Recovery on your Nexus One. ( But this is an extremely risky process and if you miss a step or do not preform it correctly, it might brick your Nexus One and Make it completely dead. So, please take responsibility of whatever you do to your phone. )
Step 3 : Flash Froyo Rooter And Get Root Permissons on your Nexus One
—————————————————————–
Now, when you have successfully installed Recovery on your Nexus One, you can proceed further with Rooting it. But if the last step was not successful, please do not proceed further and ask me in comments.
Since your phone was just wiped, you might have to enable usb debugging again so ADB and fastboot commands will work.
- Go to Settings > Application settings > Development > USB debugging (enable)
- Download and place the Froyo Rooter Signed Zip File in the root folder of the SD Card of your Nexus One. Do Not unzip the Froyo Rooter Signed file and do not place it inside any folder in the root of your SD Card on the Nexus one.
- Turn Off the Nexus One and Remove the battery for 5secs and place the battery back in the Phone.
- Now start your Nexus One in Recovery Mode by pressing the Power Button + Volume Down button simultaneously for few secs.
- Go to Recovery Using the Volume buttons to move across the menu. (The recovery screen says “Android system recovery†with green text on black background)
- If you can not go into Recovery Mode using the above step, then open the command prompt on your Computer and navigate to your Android SDK tools folder. Type “adb reboot recovery” to reboot the phone into recovery mode.
- Use the Trackball to navigate to “Flash zip from sdcard†and then select the Froyo Rooter Signed zip file to flash.
- Follow the On-Screen instructions. Press the Trackball to begin the flash when prompted.
- When the flash is complete, navigate to reboot and press the trackball to reboot.
If everything goes fine, you should have Root Access on you Nexus One with Froyo! Congratulations and Enjoy! 
( Will Update the tutorial with screenshots to make it even more easier for you to root your Nexus One. And please feel free to ask any doubts you face while rooting you Nexus One. )
It’s time to install some cool Apps that require Root Permissons to leverage the Perfomrance of your device like SetCPU, Screenshots,etc.
Let us know your Experiences with the New Rooted Nexus One with the Latest Android Froyo.
And if you are looking for some Cool and Interesting Free Apps for your Nexus One, you shouldn’t miss the Must Have Top 20 Free Android Applications List with short Reviews..