Hollywood insiders note Twitter's increasing impact at the box office - washingtonpost.com

Although word of mouth could always make or break a movie, it usually took days to affect the box office. But the rise of social networking tools such as Twitter might be narrowing that time frame to hours. And that has Hollywood on edge.

This summer, movies such as "Brüno" and "G.I. Joe" have had unexpected tumbles at the box office -- just within their opening weekends -- while "Transformers: Revenge of the Fallen" survived blistering critical reaction to become a blockbuster...