"We're still working out the details, but I'd be delighted to do the film. The problem at the moment is my busy schedule. Shooting on this film has been extended by a month, but I need to be in the U.S. by Dec. 20"

This quote by Zhang Ziyi suggests that she has an interest in doing a movie, but her current schedule is preventing her from doing so. She discusses that shooting on her existing movie has been extended by a month, and she requires to be in the U.S. by Dec. 20. This implies that she is not able to devote to the movie till her present job is finished. It is likely that she is attempting to work out the information of the film with the production group, but her present schedule is preventing her from doing so.

Zhang Ziyi's quote also recommends that she aspires to do the movie, as she specifies that she would be thrilled to do it. This implies that she has an interest in the job and wants to work out the details in order to make it occur. It is most likely that she is searching for a method to fit the film into her schedule, so that she can dedicate to it.

Overall, Zhang Ziyi's quote recommends that she is interested in doing the film, however her existing schedule is avoiding her from doing so. She is most likely attempting to work out the information with the production group in order to make it take place.