CBC radio's series 'White Coat Black Art' which is a weekly show about the medical world, industry trends and doctor/patient relationship/communication had a special on swine flu. One of the things talked about was a a recent survey which performed sampling of blood from randomly selected individuals (can't recall if it was U.S. but probably because you folks actually have money) and found about 40% of the population had titres or evidence of exposure to swine flu.
Basically most of us have already been exposed to it. The good news is that this is a mild flu strain and the fact that most of us now have had an exposure means that our bodies are developing a certain immunity towards it. Whether it mutates to something lethal or not is antibodies guess (pun). Point being, its no longer a so called new thread, just another in the list of nasty strains that can mutate into something worse in the future.