Industry analysts say took that step this week, with a little help from Warner Bros. Entertainment.

Warner Bros., a giant in the movie business, has to rent or buy and view on the Facebook site. The program, which launched in a test phase in the U.S. on Tuesday, requires users to pay $3 for the movies using Facebook's on-site currency, called Credits.

The Batman film, The Dark Knight, was the first movie available on Facebook. Users can rent the film through its official . Other movies are scheduled to be made available on Facebook in the coming months.

For a company that has quickly become the largest social network in the world, why venture into the movie-viewing business?

Ezra Gottheil, an analyst with Technology Business Research, said it's all part of Facebook's plan to become not only an online destination, but also a portal to music, movies and politics. It's also another way for to pull in more advertising and revenue.