This from The Hollywood Reporter...
The film's more than 4,366 domestic playdates is a record, surpassing the 4,362 theaters for May 2007's bow of "Pirates of the Caribbean: At World's End." Double- and triple-screening at many venues means "Dark Knight" will play on 9,200 screens in the U.S. and Canada.
Its engagements include 94 Imax venues -- Nolan shot long segments using Imax-format cameras -- and most of those giant-screen auditoriums were sold out by midweek. A Warners exec estimated that Imax presales totaled $3.5 million, with advance ticketing for other venues adding considerably to that total.