Philip's Blog

Google rolls out Android 2.3.3 for the N1 right now. It was hard to wait so long for Gingerbread, so i cant wait for the OTA update again:

- Download the update Image
- Verfiy the MD5 checksum: 706a4631271b6ee2c819ab548394b71e
- Rename the Image to update.zip
- Copy it to your SD card root
- Shut down your N1
- While powering up, hold down the Volume-Down button
- Choose recovery with the Volume-Down button and press the Power-Button
- When you see a big exclamation point, press the Power and Volume-Up button
- select “Apply sdcard:update.zip.”
- Wait until your Phone reboots

Its real and no fake. Works in Switzerland for me.
Credits goes to: trebor_88

EDIT:
Be sure that your  HBOOT Version is 0.35.0017. If you still have 0.33.0012, update your HBOOT with this update (same procedure as for the gingerbread update)

EDIT: Google removed the Download Image. Manual Updates are no more possible.
Google rolls out Android 2.2 for the N1 right now. To manually upgrade your N1 to FroYo:

- Download update Image
- Rename the Image to update.zip
- Shut down your N1
- While powering up, hold down the Volume-Down button
- Choose recovery with the Volume-Down button and press the Power-Button
- When you see a big exclamation point, press the Power and Volume-Up button
- select “Apply sdcard:update.zip.”
- Wait until your Phone reboots

You should check your Battery status before to make sure you Phone can complete the whole Update Process.

This Tutorial is confirmed to work in the UK, and now also for Swiss N1′s. I love the new Thetering Options (USB and a Portable WiFi hotspot on your N1), and the auto-Update feature for your installed Apps.

Like Euro-Droid said: “You hear that, HTC Desire owners? You’re second-class citizens already!”