OK folks here it is. THE US CUPCAKE MANUAL UPDATE LINK. got this off the Tmo forums, and it is 100% legit and it works, I just updated my phone to cupcake. Non rooted, non dev US version phone. I am so excited.
https://android.clients.google.com/updates/partner/signed-kila-ota-148830.de6a94ca.zip
For those who need help, to update manually its super easy. You plug your phone into your computer and mount it as a drive. Then you download the link above and save it as "UPDATE" on your computer (i save it in the desktop so you can find it easier). Copy the UPDATE file and paste it into your phones SD card in the main area that shows all of your folders (the root of the SD card). Make sure you disconnect your phone properly from your computer. Then, power off your phone. To turn back on, hold the HOME and END keys to power the phone on. When the G1 screen comes on, press ALT+L, then wait for the little triangle with the ! inside. Then you press ALT+S. Then the phone will begin the update. Sit tight for about 5 mins, and the phone will update and turn itself off and on a few times.
This is the real deal and legit. Thanks to all those out there who did their research and made this possible for manual update!