Christopher Paolini has reported in his newest post on the Alagaesia Newsletter that a new edition of Eragon is being worked on:
[i]”In addition to working on ELDEST, I’ve also been working with my editor on a special edition of ERAGON that will be released this fall. It will include quite a bit of information on the ancient language and the dwarf language, a brief dissertation on the origins of the names in Alagaësia, another piece of art by me—Zar’roc or Saphira flying—and an exclusive fold-out map of Alagaësia. I’m really looking forward to
Looks like we’ll be seeing a readers guide some time soon!