For those of you who have modded your Nexus One phone with Cyanogen or Desire ROM AND you want to upgrade to Android 2.2 Froyo, you can do it by just burning the Froyo image, provided thanks to @Modaco.
For people with stock Nexus One, I would advise to just wait for Froyo update rolls out. (but you can also install it too if you really want it NOW.)
Here’s step-by-step instructions on how to install Froyo Android 2.2 on your Nexus One:
1. Download the Froyo Android 2.2 image and radio files. – here
2. Put the whole zip file in the root directory of your Nexus One’s SD card.
3. Reboot the phone while holding down the trackball button.
4. Go to Fastboot then Recovery.
5. (Optional) Back up your old ROM using Nandroid.
6. Wipe to factory and also wipe dalvic cache.
7. Install the new zip file.
8. Enjoy the new Froyo Android 2.2! Hurray!
One of the key features of the Froyo Android 2.2 is that USB/WiFi tethering comes as default,meaning you no longer need to hack it to get it. ?Btw, it works flawlessly, Google did a great job of adding the tethering into native Android.
Other than that, you can also get Flash 10.1 by going to Android Market and searching for “flash”.
I have to note that Froyo is much faster for video streaming, a lot better than 2.1.
Here’s a quick video of how to install Froyo Android 2.2 on your Nexus One: