The controller on the i phone looks like a nes controller on the bottom of the screen. When you touch the buttons it reacts like pressing the actual button the controller.
The reason its so easy to do on the iphone is the core of operating system is very different than that of the blackberry O.S which is based off of the much older Java platform. Iphone was built to be an actual full functional o.s while Java much less so. I doubt if it will ever be usable on the blackberry but hey i really don't know.
I have EEMAME on a Symbian handset - it was quite cool (and hard to play with those dpads), having Ikari Warriors, New Zealand Story and Star Wars (the original vector graphics game), in my pocket on my mobile.
A SNES emulator would be great. Yoshi's Island on my phone would be great. Given Nintendo's reaction to iPhone's version of Duck Hunt (that was close - damn SureType), the success of the Wii and its virtual console will put paid to a lot of this kind of thing.
Posted from my CrackBerry at wapforums.crackberry.com