Disney (NYSE: DIS) soared to the number-one spot this past weekend with its new Pixar project, Up. The computer cartoon grossed roughly $68 million at domestic theaters as of early estimates, according to Boxofficemojo.

Disney took a lot of thunder away from News Corp. (NYSE: NWS) and its Ben Stiller comedy/fantasy Night at the Museum: Battle of the Smithsonian. That movie dropped to second place, taking in about $25 million.

According to Boxofficemojo.com, last weekend's top film, Viacom's (NYSE: VIA) Tropic Thunder, retained its number-one status over the past three days. It is estimated to have grossed $16 million at domestic theaters as of this writing. Of course, things could change, since the film currently in second place, Sony's (NYSE: SNE) The House Bunny, is only about a million dollars behind the Ben Stiller comedy. I have a feeling, though, that Thunder will keep its top spot. It seems to have some decent momentum behind it.

Death Race, released by General Electric's (NYSE: GE) Universal, came in third with about $12 million. Not too exciting of a debut. This is the kind of the film that ideally should have come out at the beginning of the summer box-office season. Since I haven't seen it, I can't say whether it would have been appropriate to have released it at that time (i.e., maybe it didn't come out that great and needed to be dumped in the latter days of August).

Dropping two places to number four is everybody's favorite superhero these days, Time Warner's (NYSE: TWX) The Dark Knight. The movie has roughly $489 million in total to its credit. It won't reach the heights of Titanic, but it will pass $500 million. Not too shabby for the Bat. I'm sure the studio division at Time Warner is working overdrive right now to construct a competent, cohesive marketing campaign to ensure that the home-video release adequately takes advantage of the incredible theatrical success that Knight has generated. They really have a big property on their hands with this one.

Has Viacom's (NYSE: VIA) Tropic Thunder succeeded where the Joker has failed? Has the film beaten Time Warner's (NYSE: TWX) The Dark Knight? According to early estimates at Boxofficemojo, it has. Can you believe it? Tropic Thunder, which stars Ben Stiller, right now has $26 million to its credit, enough to capture the top spot. That number will change most likely when final tallies are in, but it doesn't matter, since The Dark Knight is believed to have taken in a little under $17 million over the three-day weekend at domestic multiplexes, giving it a second-place finish. This is good news for shareholders of Viacom, who have so far been pretty happy with the studio's successful summer output. Box-office hits like Indiana Jones and the Kingdom of the Crystal Skull and Marvel's (NYSE: MVL) Iron Man have powered the media company.

Now, Time Warner's new animated flick, Star Wars: The Clone Wars, actually did worse than I expected. It came in third with $15 million. I admit, I totally misread this one. Believe it or not, I thought the film might do a huge number, like between $40 million and $50 million. I'm not sure the box-office dynamics at this time of year would have supported a statistic like that for this kind of film. And I guess I overestimated the number of geeks out there who were waiting to see it during the first weekend out. I really blew it on that one. News Corp.'s (NYSE: NWS) horror flick Mirrors came in fourth place, while Pineapple Express, distributed by Sony (NYSE: SNE), came in fifth. I saw Express last week. Cool movie.