Jenny, for quite a while now, "bonus" editions of the ND games have been offered, but you only receive them if you preorder the game through Her Interactive.
This particular game included the following with the bonus edition:
phone charms: extra items to find that fit with the game's theme, some very well hidden; I believe they call these items "charms" because they are reminiscent of items on a charm bracelet
charmed metagame award
secret egg puzzle
extra audio player tracks
The bonus editions of ND games do not cost more than the regular versions of the game that are available on the official release date.
If I remember correctly, the bonus editions began with Trail of the Twister and there has been a bonus edition available ever since.