DcD's ROM along with no2chem's are custom roms built by developers outside of Sprint/HTC and they use the full features of the Mogul.. like Rev a. and GPS. I have not read up enough on them but you can find there threads on this site explaining how to upgrade and the features they enable..
http://forum.ppcgeeks.com/showthread.php?t=17219 - link to no2chems thread