Time to start building those ROMs. The official Froyo/Android 2.2 file has been released into the wild for the Nexus One. This is going to be a fantastic weekend.
DO NOT TRY TO INSTALL THIS ON A MOTOROLA DROID.
Instructions for manually updating your Nexus One…
1. Download the official Android 2.2.
2. Drop the file on your SD card.
3. Rename to update.zip. (If your phone doesn’t show extensions, just “update”)
4. Turn off your phone.
5. Hold down the “volume down” button and power it back on.
6. After the phone loads some files, scroll down to recovery and press the “power” button.
7. When the exclamation mark appears, press the “power” and “volume up” button at the same time.
8. Choose “Apply sdcard:update.zip” from the menu.
9. Use the trackball to navigate to “apply sdcard:update.zip” and select it.
10. When you see “Install from sdcard complete”, select “reboot system now”.