Ok guys, this is for Newbs like myself who had to spend time figuring a lot of this out. It is the quick and dirty method of getting GB on your phone. Please keep in mind that this applies to the 1st Gen Moto-Droid only, and is only a representation of what it took for me to get GPA16 on my phone.
Step one: Root your phone. Doesn't matter how, just get it rooted. You can Google how to do that. (Personally I used Super One Click)
Step two: download the app Rom Manager
Step three: download GPA16 from Peter Alfonso
Step four: Rename GPA16 download to update.zip and place it on root folder of sd card on your phone
Step five: use Rom Manager to backup your current rom and settings (just in case)
Step six: Use Rom Manager to "Install From SD Card". Select update.zip from your sd card.
If the update doesn't work the first time, and your phone seems frozen on the screen with a triangle on it, press volume up and camera buttons at the same time bring up the menu. Use the D-Pad on keyboard to select "wipe cache" or something like that.
Wipe the cache, reboot the phone and repeat step 6.
1st reboot after install takes a while, it may even auto reboot once or twice. Within 10 mins you will be running ginger bread.
One last note: You do not need Rom Manager or other such app to do this, but for newbs like me (and you if you are reading this) it makes life SO MUCH easier.