[G1 Q&A, Help & Troubleshooting] JediDwight:
This is what I used to go from stock Android 1.6 Donut to Android 2.2.1 Froyo: http://wiki.cyanogenmod.com/wiki/HTC_Dream:_Rooting

I used the Amon-Ra 1.7.0 recovery which allows you to flash ROMs and format and repartition your microSD card.

You may be able to get the rooting and recovery install accomplished with the above guide, and then instead of going to Froyo and the new radios in the Wiki page, just go straight to the newest hboot and radios and then flash Gingerbread. But I'm hesitant to lay out the exact steps for that since that's not how I ended up doing mine.

It's kind of crazy how much you have to read and understand to go all the way to Gingerbread. You kind of have to gather up all the steps and be sure you're ready.

I mean I have the mind to go and put up an official unofficial CM 7.2 wiki page, but really I don't have enough experience with this ROM to be able to fully vouch for it yet.

After I got to CM 6.1 with the above walk-through I had to install the Android SDK and flash the 0013d hboot and the 2708 radio, which is done with fastboot mode with the G1 connected to your PC with USB. I found the commands to do that and copied and pasted them from a forum page into the command prompt window to do that. To boot the phone into fastboot mode, it is off and you hold down back and tap the end/power button and let up on back after a couple of seconds. Then with the phone connected you can use the command line commands from the SDK.

Recovery mode is holding home and pressing power (from the off state).

My next steps were to reboot into the Amon Ra recovery, flash the Ohsaka superwipe ROM, reboot into recovery again, and reformat the SD card. Then I did the Toggle USB-MS (this mounts your G1 as a USB drive) and copied my CM 7.2 ROM zip, the auto-boot-2.6.35.13-farmatito-pershoot-ds+-20110505 kernel zip file, and the Google Apps zip files from my PC to the card, and flashed those files in that order, then reboot normally. The first boot may take a while.

I think it's advised to wait and get the phone charged up to 100% before flashing ROMs.

I got my Farmatito Pershoot kernel from here. The kernel I used is Standard Autokernel for Gingerbread (stable): auto-boot-2.6.35.13-farmatito-pershoot-ds+-20110505.zip It may not be the absolute latest Linux kernel, but it works with Gingerbread and the new radio and it works with Deep Sleep mode to give you the best battery life. (And a new battery can work wonders.)

the new hboot and radio are over in this thread.

The Gingerbread ROM I currently have is dw9906's Unofficial CyanogenMod 7.2.

You want this file: signed_update-cm-7.2.0-DS.zip and the Gapps zip file. For future reference you want MDPI apps and themes - medium DPI for the first generation Androids versus the newer 4-inch phones.

That page said to install Simple2Ext off of the Market first thing, and I missed that so I'll be wiping and redoing my phone before long.

You probably want Google Maps 4.7 which you can install manually off of the SD card after you are booted into the new ROM. I see that Gingerbread no longer comes with Gmail or Maps, and this older 4.7 is supposed to be easier on resources.

And for these XDA threads that I linked, Post #1 is most important with the instructions and URLs since the beginning and middle of the pages' long threads cover old stuff that has since been fixed.

A big hangup on all of this is that very recently MultiUpload.com is down, and that, along with offering free downloads, had links to the same file on other services. So if you find something like the kernel that you can't get, you may have to try Googling the filename to find it hosted someplace. And I use WinMD5 for verifying that the file download hash matches. Or also try to search for the MD5 hash just to see if you can locate the file.