Movie trends usually come and go within a year or two, but one trend that seems to have remained consistent is the tendency for more and more films to be shot in widescreen "Scope" format -- the 2.35:1 aspect ratio rather than narrower screen formats.
We've most recently seen this with animated movies. For many years, a huge majority of animated films were shot in non-wide formats. Disney experimented with 'Scope in the '50s, but gave up on it pretty quickly. (Which was a very good decision, since TV broadcasts were so important to his movies, and by not using widescreen, he made the films much more TV-friendly.) All the '90s Disney movies and Pixar movies were in non-wide aspect ratios. When Brad Bird made The Iron Giant in Panavision, he was, as with much else about that film, going against the grain. But now, widescreen is common for animated features, and not just Brad Bird features: John Lasseter switched to 2.35:1 for Cars, Andrew Stanton used 'Scope for Wall-E, and over at DreamWorks, Kung Fu Panda is their first 2.35:1 movie.
I keep seeing this all over the place, where movies that a few years ago would definitely not have been widescreen are being done in widescreen. And more filmmakers seem to be switching to the format for their recent pictures; the Coen Brothers almost never used 'Scope unless it was for an epic subject like O Brother, Where Art Thou?, but when they made No Country For Old Men, a crime drama that they would normally have shot in 1.85:1, they shot it in widescreen. Martin Scorsese did most of his movies in 1.85:1 in the '70s and '80s; now almost every movie he makes is in 'Scope. And so on.
In the '70s and '80s there was a trend for moviemakers to switch the other way, from wide to non-wide, as a backlash against the overuse of 'Scope in the '50s and '60s. (Like at Fox where they mandated that every film they made had to be 'Scope, no matter what the subject.) The late Sydney Pollack, as I said in an earlier post, made every movie in 'Scope up to the mid-'80s and then switched. By the '90s, the general rule was that a movie would not be in 'Scope unless it was a big subject -- action movie, epic -- or unless the director preferred 'Scope for some specific reason. (I.e. a director like Blake Edwards who just preferred to compose shots that way.) Now it seems like unless a director specfically prefers 1.85:1, like Sofia Coppola, Judd Apatow, a few others -- the "default" format for a movie is 'Scope.
I can't quite figure out why this has happened. Maybe it has something to do with the increased availability of widescreen TVs; directors want the theatre experience to be different from watching at home, and that's harder to come by if the movie screen is the same shape as a modern TV screen. Another possibility is that modern cinematographers tend to prefer widescreen and unless the director has a strong preference one way or the other, a director will tend to go along with what the cinematographer wants. Bill Clothier, the great photographer of Westerns said in a (surprisingly acerbic) interview that he preferred 2.35:1 because it allowed for more interesting compositions than 1.85:1; he hated that aspect ratio because it was a weak middle ground between the old 1.33:1 shape and the wide screen, and didn't have the advantages of either format. (1.33:1 is a great format for medium close-ups, two-character dances, and stuff like that; 'Scope is good for tighter close-ups and panoramic shots. 1.85:1 is kind of just there.) Other cinematographers like Gordon Willis have said that 2.35:1 is their favorite and that they would have liked to use it more often than they did. Maybe a new generation of cinematographers is just getting its way. That doesn't explain the rise of 2.35:1 in animation, though.
Update: As noted in comments, Pixar did make one widescreen movie in the '90s, A Bug's Life.