NES.app emulates the hardware in a Nintendo entertainment system, allowing you to play games on your iPhone. There are many public domain, home-brew games available which have been written for the Nintendo platform, and depending on your country of origin, you may be entitled to play images of commercial games which you rightfully own.

Thanks to http://www.1emulation.com for the news.

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