Coming soon says
First reported last month, a six-minute prologue to The Dark Knight Rises is going debut with Paramount Pictures' early release of Mission: Impossible - Ghost Protocol in IMAX theaters on December 16 (the film has its general release on Dec. 21). Today, confirmation arrives that the footage even has an MPAA rating. It's going to be PG-13 for "some violence".
The plan matches the screening situation in December 2007 where The Dark Knight attached its opening sequence to IMAX prints of I Am Legend.