The basic premise is similar to Kornbluth's classic story, except the average Joe protagonist wakes up in a world that's completely inhabited by dumb white trash and their black/Latino/Asian counterparts. No secret cabal of inbred scientist/engineers running the world here. He winds up being tasked to save America's dying food crops, fix the economy, and deal with the mountains of garbage that threaten to inundate the cities, precisely because after five centuries of devolution, he's the smartest man in America. It's funny and sad by turns, watching him try to cope with a country that's been dumbed down to the point of nearly-complete dysfunction - you wonder who, if anyone, is fixing things when they break or get shot up by the insanely trigger-happy police.
There's not a lot of deep philosophy in this movie, but despite that it'll make you think a little bit; it also has a happier ending than Kornbluth's story, which is another plus. It's available on DVD, and you really ought to check it out.
Disturbingly enough, on the way in to work on the 535, the back passenger-side corner of the bus was occupied by an overweight couple who sounded like they'd been extras in the movie, only without the brightly colored, logo-adorned clothes.