Attention Nexus One Owners-
Froyo has been released into the wild but the rollout, as usual, is slow, so here’s a quick way to get it up and running on your Nexus One now. If you have a rooted Nexus One then you’re going to have to wait for folks like Cyanogen to cook up a new ROM based on 2.2.
(More on Techland: Hands-on With Android 2.2 (Froyo) and Flash 10.1)
Step 1. Download Froyo to your desktop and rename the file to “update.”
Step 2. Copy the zip file to your Nexus One’s microSD card.
Step 3. Power down your Nexus One.
Step 4. Press the trackball and power button until the three skating Android show up.
Step 5. Use the volume rocker to highlight “bootloader” and select with the power button.
Step 6. Use the volume rocker to highlight “recovery” and select with the power button.
Step 7. Your Nexus One will reboot and you’ll be presented with an Android and an exclamation point. Press the power button and volume up button.
Step 8. Select “apply sdcard:update.zip” with the trackball and you should be good to go after a few minutes.
Step 9. Enjoy.
P.S. – Don’t forget to download the Flash 10.1 Beta from the Android Market after you’re running 2.2.