Wow-- something I've noticed after my little vacation last week is that the iPhone application community is at a full sprint (no pun intended) on making applications. When I left, people were dropping Hello World, and now we're up to the evolutionary step of NES emulator. By this time next week, we'll have a screenshot grabber (oh wait, we've already got that-- guess it's time to go for Open Office).
Wily programmer "stepwhite" has brought the InfoNES core onto the iPhone, along with Mario, Zelda, and all your favorite NES roms. As you can see, it's not quite done-- the emulator runs too slowly to be playable, and the controls are implemented with an actual controller image which, as the programmer says, "...while cute, sucks."
I don't know if theres any way to save states, either. Not a problem for Super Mario Bros., but Dragon Warrior or Final Fantasy might be a little long to have all in one go. But it is awesome, and just amazing that we've already gotten to this level on the iPhone. At this rate, we may not even need an SDK.