A recent article in the New York Times explored the way that The College Board is "Rethinking Advanced Placement." The focus of the article was on AP Biology and AP US History, but the overall philosophy of the change is moving from an emphasis on memorization to an emphasis on the skills and processes of the discipline. For my part, I think this is a needed change to keep--or finally make--the tests relevant to colleges.
I would compare this to the two English tests, the AP English Language and Composition (usually taken junior year) and AP English Literature and Composition. I have a fair bit of experience with both and can say that both do a relatively good job of testing skills rather than, for instance, particular works. Although I spent a couple years teaching an AP English Language and Composition course, what it really amounted to was tracking the juniors who were the stronger readers and writers into a separate class, not a year of cramming for the test. One school at which I taught didn't have any specialized course, just a couple nights going over the format of the test for any juniors who wanted to take it. I make a point of all this because the nature of the test allowed for students who were good readers and writers, who could analyze others' arguments and make their own, to do well.
In other words, by and large the same things that the test looks for are the things that college professors--and good high school English programs--look for from their students.
Years ago now, I read James Loewen's Lies My Teacher Told Me, which examined high school American history texts and courses, and one of Lowen's assertions was that high school history (largely "social studies") programs do little to prepare students for university history programs. In fact, college professors in history have to spend their time at the introductory level unteaching students, because the study of history is not a collection of facts but a toolbox of skills to utilize the sources from which we learn about history and to make and interact with arguments about not only what happened but also why it happened, how it happens, and the like (if I seem vague, I'll confess that it's because I have only a layman's view of what historians actually do).
Although it is perhaps not as profound of a gap, the same thing seems to exist in the sciences, where learning science in high school is often a rather different enterprise than the practice of science at the university level (to say nothing of doing science as a profession). AP classes purport to be doing college-level work, but in some disciplines it seems that the AP tests have more or less prevented that from happening.
I believe that one of the effects of this rethinking of many AP tests could be that it puts a greater burden on high school departments as opposed to the teachers of AP classes. Again, I go back to my experience at the school where students were, essentially, prepared to take the AP Language and Composition test not by a class but by their overall experience in the discipline over the course of three years. We trusted that students, at each grade level and by each teacher, were achieving the same goal that our department chair set before us: make them better readers and writers. And by doing that, we prepared them not only for tests but for college and beyond. The alternative is that one teacher tries to teach the skills and processes of the discipline in just one year (or, on a block schedule, one semester)--I'm sure it can be done, but I should think by far fewer students than could achieve a similar level of competence through a couple years of poor to mediocre classes followed by one "AP" class. Now, if all we want from our students is to memorize a boatload of "facts," that can more or less be done in a year (which is not to say that it's easy to do so--or particularly worthwhile).