Advertising budgets for the release of a film are massive, and for the most part, formulaic.
If a studio thinks a film has a chance at grossing north of $150 million domestically, it will lay out $100 million or more for a worldwide campaign. For a film that's hoping to gross $50 million or more domestically, a studio will spend $30 million-$40 million. (source: Variety).
The bulk of ad budgets are spent on TV and radio, and historically, in newspapers where viewers traditionally visited to check out film show times and locations. But as viewers/readers have moved from newspapers to digital media, so have the movie marketers.
Newspapers are out, while text messages, social networks and other Web sites are in.
From Variety:
And while studios spent about 14% of a film's marketing budget on newspaper ads in 2004, and 10% as recently as 2007, they now allocate maybe 4%, according to studio insiders.