Share '"The Dark Knight" delivers best opening day gross ever!'

Source: Variety The domestic box office went into overdrive on Friday as Warner Bros.' Batman sequel "The Dark Night" stood ready to deliver the best opening day gross ever, taking in an estimated $60 million to $63 million in ticket sales from a record 4,366 theaters. Universal's film adaptation of musical "Mamma Mia" was no wallflower, either. The Meryl Streep-Amanda Seyfried starrer -- the id…