The LATimes has a list of Best & Worst 2008: Most shocking headlines, and Catherine leaving is part of it:

Catherine Hardwicke leaves ‘ Twilight’ franchise

Fans and studio execs alike were nervous that the film adaptation of the first of Stephenie Meyers’ beloved teen vampire novels would fail to satisfy her devoted and fiercely protective fan base. When the film satisfied both fans and non-fans alike, everyone breathed a sigh of relief and began to eagerly anticipate the already green-lighted sequel, “New Moon.” So it was a real stake in the hearts of many fans to hear that director Catherine Hardwicke and Summit Entertainment were parting ways and that a new director would be brought in for “New Moon” (“Golden Compass” director Chris Weitz). To make matters worse for Hardwicke, who seemed more than happy to ride the undead gravy train to its conclusion, the announcement of her departure was made just as she was preparing to promote the movie overseas.

Source & more of the list.