Twilight Saga: Breaking Dawn may just be well start the shooting this autumn, as rumoured by the LA Times. The shooting may start shortly after the release of the third installment Eclipse this summer, according to the series producer Wyck Godfrey.However, the big deal is that the casts aren't signed for it yet. There is also a running rumours whether Summit Entertainment will split the movie into two or not, as reported here at Green Tea Movie, while the script for the fourth installment is not really ready yet.
Perhaps, the most difficult things to do is that Breaking Dawn will be need to be settled are the effects for certain scenes, as highlighted below:
SPOILERS There are also some effects challenges presented beyond the body-horror aspects listed in the link above; the second half of the book features a half-human, half-vampire infant who is walking and talking by the time she's about a week old, requiring massive amounts of CG either in conjunction with or instead of an actual baby actor. END SPOILERS
SOURCE: LA Times and Empire Online