What The Post-Credits Scene Means
The end scene is explained by the first scene, particularly the part discussing the ideas of Norman Mailer. The idea is that we have a tendency to try to understand things that aren't related (In Mailer's example the Kennedy assassination). Why this matters is that in trying to understand a connection between two unrelated things Sydney was saved in the movie, this post-credits scene can be interpreted as trying to do the same for the audience.
This is made all the more obvious by Grant Mazzy in the post-credits scene saying "anticeptualize", a post-modern way of saying the opposite of conceptualize. Seeing as conceptualize is a way to understand, it's opposite (anticeptualize) would mean trying to undo or negate or break apart that understanding. Again exactly what Grant did to Sydney to save her.
Anyone who doubts the significance of the Mailer reference, must acknowledge the Mailer radio segment is played twice throughout the film and one of the characters even emphasizes it by saying how much she likes Mailer.
Opening lines:
Grant Mazzy: Mrs. French's cat is missing. The signs are posted all over town. "Have you seen Honey?" We've all seen the posters, but nobody has seen Honey the cat. Nobody. Until last Thursday morning, when Miss Colette Piscine swerved her car to miss Honey the cat as she drove across a bridge. Well this bridge, now slightly damaged, is a bit of a local treasure and even has its own fancy name; Pont de Flaque. Now Collette, that sounds like Culotte. That's Panty in French. And Piscine means Pool. Panty pool. Flaque also means pool in French, so Colete Piscine, in French Panty Pool, drives over the Pont de Flaque, the Pont de Pool if you will, to avoid hitting Mrs. French's cat that has been missing in Pontypool. Pontypool. Pontypool. Panty pool. Pont de Flaque. What does it mean? Well, Norman Mailer, he had an interesting theory that he used to explain the strange coincidences in the aftermath of the JFK assasination. In the wake of huge events, after them and before them, physical details they spasm for a moment; they sort of unlock and when they come back into focus they suddenly coincide in a weird way. Street names and birthdates and middle names, all kind of superfluous things appear related to eachother. It's a ripple effect. So, what does it mean? Well... it means something's going to happen. Something big. But then, something's always about to happen.