Freedom of expression suddenly has an unlikely champion: Wal-Mart.

The family-minded chain has embraced “Brokeback Mountain,” Ang Lee‘s ode to gay cowboys, stocking the recent DVD release on its shelves and actively promoting it to shoppers.

The move is something of a moral flip-flop for the retailer, which has worked to keep more provocative content from its shelves: It doesn’t carry CDs labeled with parental advisories, only edited versions. It nixed men’s mags like Maxim and Stuff a couple of years ago, and even hides saucy coverlines on mags like Cosmo.

The retailer’s stocking of the film comes over the objections of the American Family Assn., the Christian org founded by Donald Wildmon. The Mississippi-based group is urging members to boycott Wal-Mart in protest.

But the chain reports brisk sales for the multi-Oscar winner since its April 4 release on disc, suggesting that at least some of its shoppers do like making their own content choices.

“Customers continue to vote at the cash register,” says a rep, who declined to quantify sales. Wal-Mart rarely discloses DVD sales info.

Universal homevid declined to comment on Wal-Mart’s “Brokeback” activity, but is pleased with initial sales overall. “Brokeback Mountain” sold more than 2 million units its first week, a strong showing that a rep says underscores the disc’s broad appeal.

American Family Assn. activists have complained most about how prominently Wal-Mart is promoting “Brokeback” in stores, noting that images from the film appear in the front of stores, not just DVD sections. Wal-Mart’s rep says the chain promoted the title the same way it does any other major new release.

“We carry the latest titles because typically that’s what people want,” says the rep, adding that the chain carries a broad array “to meet the needs of the diverse consumers that shop our stores.”

Unlike its policy on CDs, Wal-Mart doesn’t insist on edited versions of films that have objectionable content (like Blockbuster, though, it doesn’t carry NC-17 films). But it did draw the line at carrying Robert Greenwald‘s critical doc about the chain.

The chain hasn’t shied away from some controversial pics: Clerks at Los Angeles-area stores say they used to carry “Fahrenheit 9/11” and “Super Size Me,” but returned their unsold copies to studios.

“I’m not supposed to tell you this,” one whispered into the phone, “but you might try Best Buy. Sometimes they have more selection.”