Pic via National Post
I've been doggedly looking for a timeline for when the next series in the trilogy that began with The Passage and finally thought, "Hey! Let's check Wikipedia" where I found the above link and the following information (also from National Post):
[Cronin is] hard at work on the next instalment in the trilogy. The Twelve is due in 2012, while the concluding novel, The City of Mirrors, will hit stores in 2014.
Also Ridley Scott's production company bought the movie rights to the first book! Yes! Exactly what this book needs: an intelligent director with a sense of style who isn't SO popular that the movie will degrade into a simple gore-fest!