The definitive site for Motorola hacking, upgrading, etc. is Motclub, http://www.motclub.com/.

Unfortunately for some of you, it's based in Spain and all in Spanish except for one seldom-visited forum.

You can probably pick your way through using Babelfish or something. They have a ton of information there, including pointers to the little pieces you need that are scattered all over the web.

Motorolas are the funnest and easiest to hack that I have yet seen. I bought a V400 for $200 and was able to update the firmware from the crappy Cingular stuff to generic, and change the flex...now it thinks it's a V600, complete with all the applications and features (funny the Bluetooth menu doesn't seem to do anything though)...

I just ordered an A630 (finally) and will be hacking the nuts out of it to enable video, quadband, IM, etc.