Apparently not. According to Prufrock's Gifted Education Blog, while AP classes may be a boost to the high school GPA, it is only the tests that are a good indicator of how you will do in college. How can this be? Well, apparently schools are adding "AP" to just about all of their college prep classes, whether there is an AP test for that subject or not. (AP Ceramics, anyone?) And not all classes are doing a good job of preparing their students for the AP tests. This has led to the College Board deciding to audit and certify AP classes starting in 2007.
On another list, I heard some schools are offering "Pre-AP" classes as well as AP classes. There are also cramming classes like they offer for the SAT and ACT, etc. Methinks you'd be better off just getting one of the many AP guides on the market and studying by yourself instead of wasting an entire year in a class of questionable merit. Of course, that's quite a bit like homeschooling... LOL
Don't get me wrong. My senior year I took three APs: English, US History and Biology. I loved them (except Biology) and did well on the tests (except Biology, but at least I passed!). Those were the first classes where I really felt I was learning something, the class moved at an appropriate pace and I had to put in some effort in to keep up. Finally! So I think AP classes can be a god-send for a gifted high school student. I can only hope that once the College Board beings auditing these classes, they'll be such a good environment for every AP student.