Back in October Boy Genius Report reported that the iPhone would be coming to Wal-Mart soon, but to this day that has yet to happen. According to Mac Rumors the official release is pinned for December 28th and Wal-Mart staff have already begun receiving training.
Today Boy Genius Report is also claiming that Apple will reintroduce the 4GB iPhone and it will be sold for $99 with a two year contract. BGR does warn that it is not 100% confident about the report so it should be taken with a grain of salt.