Steve Spielberg confirmed during the Tim and Tintin Panel at ComicCon 2011, they will have a writer and the story for Jurassic Park IV and going into production within the next 2/3 years.

http://www.digitalspy.co.UK/Movies/News/a331257/Jurassic-Park-4-in-two-or-three-years-Says-Spielberg.html

View the original article here