Jaz said:
I think we're a little ahead of ourselves yet. But I have no doubts that in a few handsets time, we'll see emus running on cellphones.
Piece of cake.
Some phones, such as Nokia Communicator running EPOC32 OS, almost the same as Psion PDAs.
I have Gameboy, Spectrum, PC XT, C64, Apple II and even... MAME (no, no Neo-Geo, CPS-2 support

, only Z80 oldies - Pacman, Galaxian etc) for my Psion and i'm currently working on SMS/GG/NES/A2600/A7800 and maybe more systems emulator for EPOC32.
There's a little difference between Psion and Commie's OS. Psion uses ER5, Communicator ER6, but it's not a problem. Go to eGNUBoy and eMAME
official site
and grab sources, then download SDK for Communicator (AFAIK its free), recompile for Commie's screen size, and voila !!! You have MAME on your phone
