Consider that real rain is formed when the moisture from the earth's surface (lakes, oceans, whatever) is drawn up into the atmosphere and then condenses into droplets. To have meatball rain, you'd have to have something that draws cows up into the atmosphere and then grinds them into a paste with bread crumbs and oregano and then cooks them before dropping them back to the planet.

Imagine it: Instead of the sound of distant thunder foretelling rain, it will be the sound of terrified mooing. "Bessie's making an awful sound, Grandpa." "Well, Billy, we must be in for some rough weather!" Instead of the distinctive odor of ozone, it will be the smell of olive oil and rendered fat that accompanies a storm. The rivers will run red with blood and marinara sauce. Umbrellas will be made of crusty garlic bread. Motherless calves will wander around, lowing pitifully, until they, too, are sucked up into the atmosphere to become a deluge of Wiener Schnitzels.

Are you hungry yet? The film has a January 15, 2010 release date.