I don't know about Jurassic Park 4. I just heard about it, and the third one wasn't very good. I was hoping Jurassic Park 3 would have something to do with the shaving cream bottle from the first one (the one that denis dropped before getting torn to shreds by the dilophosaurus). That scene seemed like it was a subliminal message that Spielburg left for us, but it seems i was wrong. Oh well, i've dreamt there would be a fourth one ever since the third one came out. I always imagined that no one would want to see the fourth, because of how bad the third one was, but it might turn out to be better than the third, and possibly the second, since Spielburg will be helping produce it. I have no idea, but one can dream, can't they? Perhaps this one will mark the ending everyone was hoping to see in Jp3. I guess we'll just have to watch it and find out for ourselves.
keira knightley being in the movie was an uncomfirmed rumor, and i believe she stated a long time ago that she had no plans to be in it.
also, another rumor out there regarding the plot is that the dinosaurs will somehow be taken in by the army for their uses, such as strapping guns on their backs, or using some sort of mind control device. that's supposedly mr. spielberg's big idea, just a rumor, of course.
man, does that idea suck.