As per this article, the Da Vinci Code movie will likely be a disaster, possibly reduced to nothing more than a car chase.

"The film version of The Da Vinci Code is attempting to reduce the offence that the best-selling book caused to Roman Catholics.

Sony Pictures, the studio behind the film starring Tom Hanks and Sir Ian McKellen, is reported to have been so concerned that it has consulted Catholic and other Christian specialists on how it might alter the plot of the novel to avoid offending the devout.

The studio has been asked to consider whether the central premise — that Jesus had a child with Mary Magdalene — could be more ambiguous and whether the name of Opus Dei could be removed.

'There's no way you can take out the central point of the novel, that Jesus married Mary Magdalene and the Catholic Church has done everything in its power, including murdering millions of people, to cover it up,' said Carl E. Olson, co-author of "The Da Vinci Hoax," a book refuting the The Da Vinci Code. He predicted that many devout people would be offended 'unless they make a movie that bears a pale resemblance to the book, in which case they'd have a lot of irritated fans.'"

The New York Times has an article on this as well.