The iPhone is officially a "closed" architecture, meaning only Apple, and people with Apple's blessing, can write applications for it. In reality, the platform is anything but closed, as industrious hackers have dug into its software guts and figured out how to run applications, , including Nintendo games, on it.

Officially, the only third-party apps that run on the iPhone are supposed to run inside the Safari browser. But when have hackers played by the rules?

A programmer going by the name "stepwhite" brought the InfoNES core to the iPhone, along with games like Mario and Zelda, according to The Unofficial Apple Weblog.. TUAW notes: "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.' "

Hackers "Nervegas," and "NightWatch," a/k/a Patrick Walton, have an optimized NES emulator that runs faster and with multitouch support. "iPhone NES: the game for big hearts and small thumbs," TUAW quips.

TUAW has been on fire with this stuff. They've developed a screenshot utility, recorder, and basic word processor.

I'm in no rush to mess around with this stuff -- I want to keep my iPhone stable and crash-free. Still, it's great to see others getting into the guts of the iPhone and hack it.

I expect that the iPhone's closed, proprietary architecture is temporary, and that Apple will come out with an SDK to allow developers to build supported applications, possibly based on technology included in the Leopard update of the desktop Mac OS X, due out in October. Till then, the iPhone is a hackers' playground.