The rumors are flying about gaming giant Nintendo licensing "a limited amount of content" for the iPhone, and the rumors all seem to point back to this post over on a site called No Heat. They name no sources (of course), but they say that these Nintendo games will show up on the iTunes store at $29, and say that the games will "cater to an older audience."
Now, if anyone is going to provide great gaming content on the iPhone, Nintendo would be a good fit-- with the touchscreen, they've already got some great properties set up on the DS (Brain Age would be a great fit, and of course all of their famous licenses). There are lots of great input methods that I'm sure Nintendo would love to take advantage of.
But $29.99 is a steep price for a mobile entertainment game, even if it's Mario. Super Nintendo games are running about $10 on the Wii's Virtual Console, so either a) Nintendo is going to make iPhone owners pay through the nose, b) the games will be DS quality-- because $29 is about what you'd find a new DS game for, or c) No Heat is making it all up, and this is just another product of the iPhone rumor mill.