Last month, Warner Bros. confirmed it will attach a six-minute prologue of The Dark Knight Rises to 70 MM IMAX prints of Mission: Impossible Ghost Protocol starting December 16. Today the MPAA announced it will give the prologue a PG-13 rating, for "some violence."
The report from October also indicated the prologue will not screen on all IMAX digital screens, only 70 MM IMAX screens. Of course, this rating doesn't automatically mean The Dark Knight Rises in its entirety will be rated PG-13. However, since Batman Begins and The Dark Knight were both PG-13, it seems incredibly likely that The Dark Knight Rises will be released with the PG-13 rating.
Christopher Nolan is directing The Dark Knight Rises, which is still shooting in New York City. Warner Bros. used the same tactic four years ago, when it attached a prologue of The Dark Knight to prints of I Am Legend in December 2007.