Porting from TGB to handhelds?

I was wondering if anyone had any experience or even a vague idea as to what trying to port a TGB game to a handheld system (doesn't matter which; DS, PSP, iPhone, or anything similar) might entail. I am interested in creating a platformer and trying to have it published on one of these systems. Please share your experiences with me!

It looks like there is an engine for deploying TGB games to the iPhone, has anyone tried it? How difficult is the process? Are there forums somewhere dedicated specifically to this sort of thing, is there a site where I can go to educate myself? Any help would be appreciated.