iPhoneNES is a NES emulator for iPhones.

Changes:

0.21 nervegas Added support for external audio / switch added for earbuds
0.22 stepwhite Added diagonal direction hotspots, SHOW_HITSPOT flags
0.23 nervegas Tweaks to orientation change, DEBUG shows hot spots now
0.24 nervegas Using K6502_rw.h from older core, Metroid and Punchout work! Made more improvements to orientation sensitivity. Implemented slightly faster rendering
0.25 nervegas Enlarged controls for landscape mode
0.26 nervegas Change status bar background to black on landscape
0.27 nervegas Controller fix to allow button, then directional pad hold
0.28 nervegas Added save SRAM support (to save SRAM for games like Zelda)
0.29 nervegas Added auto-save state and “Saved Games” selection
0.30 nervegas Fixed SaveState for many games, +Mapper1 +Mapper5. This fixed Tetris, Bubble Bobble, Super Mario 2, others…
0.31 nervegas Fixed SaveState for Mapper4 games (Earth Bound Zero, etc)

http://code.google.com/p/iphonenes/