The weekend estimates have The Dark Knight taking the top spot for the fourth straight week in another squeaker -- though not as close as last week's victory over The Mummy: Tomb of the Dragon Emperor. It dropped 39% to $26 million, which was good enough to beat the $22.4 million showing for the stoner comedy Pineapple Express. That brings The Dark Knight to $441.5 million, edging out Shrek 2for third place on the all-time domestic charts. By next weekend, it should pull ahead of Star Wars (its unadjusted numbers, anyway) for second place. Titanic still remains out of reach, or at least it seems that way right now.

It's worth noting that Pineapple Express was released on Wednesday (since Wednesday's the new Friday, doncha know), and pulled in $40.5 million over the five days -- a victory for an R-rated stoner comedy. The horribly titled The Sisterhood of the Traveling Pants 2, also released on Wednesday, had a $19.7 million five-day on just over 2,700 screens, a reasonably strong showing for a sequel to a niche film that made $39 million in 2005.

The Mummy: Tomb of the Dragon Emperor dropped 60% to $16.1 million -- whoops. It looks to top out at around $100 million, which would make it a distant third in the main franchise, though it might beat out The Scorpion King.

One of the summer's biggest box office surprises is lurking down at #7 on the weekend chart. Journey to the Center of the Earth continues to suffer only miniscule drops; it's taken in $82 million after five weekends of release, after an opening weekend of only $21 million. That sounds like a ringing audience endorsement of Real-D 3-D to me.

The full estimates after the jump.