Here's a great obituary for Michael Crichton that came to my attention today.

One of the items that has me wondering was what his next book was going to be like. HarperCollins, his publisher, had scheduled for his next book to be released in December, but his illness postponed its release indefinitely. 

The private illness Crichton's family kept out of the media doesn't tell us much regarding how long he was ill. We can't really be sure how much of the novel was complete before his sickness postponed his efforts. Either way, we also don't know whether or not his final work will be finished or published posthumously. 

I can't even find any clues as to what it was about, but it should be available next May. So we'll get a glimpse of it.

Wikipedia has an excellent article on Crichton, if anyone was interested in more of his thoughts.