NES.app is a fully functional, feature-rich Nintendo emulator for Apple’s iPhone.

NES.app uses a heavily modified version of the InfoNES emulation core to mimic the 6502 processor in a Nintendo Entertainment System, allowing you to play ROM dumps of games designed for the NES console. ROM dumps are files containing the dumped instruction code from a physical cartridge. In many cases, you are legally entitled to posess a ROM dump of any game that you presently own. ROM images for NES are widely available online, or with the appropriate hardware, you can dump them yourself directly from the cartridge.

NES.app started as a fork of iPhoneNES v0.01, but has been completely rewritten to run very fast, and with many additional features including sound, multitouch support, full-screen, landscape mode, game genie codes, saved games and much more.

Changes:

[jonz] Added saved game icon next to saved games in all browsers
[jonz] More code cleanup
[jonz] Improved swiping, removed false swipes when scrolled from center

http://www.zdziarski.com/projects/nesapp/