**EDIT** Figured if I have a post here, it might as well be useful.
Here is the update:
Google Download: https://android.clients.google.com/u...-RC19+RC28.zip
**This download might need to be refreshed once or twice before it works. If you get 503 server error, try again, if it doesn't work after a while use the links below.
Rapidshare Download 1: http://rapidshare.com/files/15924331...-RC19_RC28.zip
Rapidshare Download 2: http://rapidshare.com/files/15924473..._RC28.zip.html
Rapidshare Download 3: http://rapidshare.com/files/159411433/update.zip.html
(Must be registered)
Steps to upgrade:
1: Download the file and rename/save it as update.zip (some users found just plain update works best (no .zip))
2: Place the file on your mini SD card and insert it into your G1 (card formatting requirements still unknown, so if fat does not work, try fat32 and vice versa) with THE PHONE OFF
3: While the phone IS STILL OFF, Hold down the "Home" and press the power button (end call) (keep holding "Home"
3: Wait for
open your keyboard and press Alt+L
4: When you see yellow text, pless Alt+S
5: When it says "Installation Complete" you can press "Home" + "Back" to reboot.
6: Wait for your phone to completely reboot and allow it to finish writing your radio rom during reboot
These instructions are paraphrased from other users and are not written by me.