Harry Potter & the Half-Blood Prince
Now I've seen it, and liked it; the best since Prisoner of Azkaban. There are some fairly major deviations from the book, but I'll hold off on spoilerific specifics for a while. Here's a teensy one: The movie accomplishes the difficult task of making Harry/Ginny believable.
A parody is probably coming one of these days, but I'll have to see it at least once more first.