You might expect The Onion Movie to be just an extension of the website: The Onion. Lots of Area Man and Local Sports Team news in more or less disconnected sketches. Good guess. If you guessed movie with a plot, you get only partial credit.
The movie resembles Kentucky Fried Movie, and other sketch type comedies. It kind of uses a news show as a framework - there is subplot about an anchor disgruntled with the network pandering to its entertainment corp. parent. But this is more of an excuse to hang a silly kung fu movie and some poptart music videos on the framework.
It's pretty funny, although I don't think Area Man shows up at all.
And David Zucker (Airplane, etc) is included as executive producer, probably because he owns the genre.