On August 22, 2009, Cassandra Clare and many loyal fans met in Central Park for an event. At this event, Cassie announced that The Mortal Instruments would be made into a trilogy of films. Below is that announcement.
Unique Features to Develop and Produce a Trilogy of Films Based on Cassandra Clare's Mortal Instruments
New York, NY - August 22, 2009 -- Bob Shaye and Michael Lynn's Unique Features will develop and produce The Mortal Instruments, the trilogy based on the supernatural New York Times Best-Selling young adult fantasy series of the same name, written by Cassandra Clare.
"We are excited to be developing and producing the fantastic written by her and look forward to bringing her fantasy series to the big screen," said Bob Shaye and Michael Lynne.
Status
Cassandra says herself that film rights being optioned definitely doesn't mean that a movie will really happen, so we basically have to take all of this news with a grain of salt. After announcing the news, she posted this on her LiveJournal:
Now, a book series being optioned doesn't mean a film is being made right now or is definitely going to be made at all — it means that the studio or production company in question is developing the books as a film project — right now they've nailed down financing and a screenwriter (I don't know who that is yet) and are working towards the next stages in the development project. It is, however, an important step in the movie-making process, so I feel like it's okay to be excited about it. :)
They later secured a screenwriter-- Jessica Postigo--and the script has been completed. The next step is to find a director, which they are in the process of doing.
Movie news! The script for the first Mortal Instruments film is complete and they are now on to finding a director for the film. The screenplay was written by 
Clockwork Angel, the first novel in the Infernal Devices trilogy, will be released on August 31, 2010. You can find art with the characters from CA