The Wall Street Journal has launched an iPhone app and—strikingly for a company that safeguards the bulk of its online content behind a paywall—it’s free. Granted the company doesn’t charge for its Blackberry application either—and every page in the new iPhone app is underlined with a prominent ad. But don’t get too attached: A company spokesman reminded us that the “intent is to ultimately have a consistent experience across multiple platforms regarding subscription content.”

Still, the decision not to charge for the moment seems especially odd considering that News Corp (NYSE: NWS) Chairman Rupert Murdoch recently complained: “People are getting used to getting everything on the net for nothing. That’s going to have to change somehow.”

The company has also had relative success getting Amazon (NSDQ: AMZN) Kindle owners like Martha Stewart to pay to get the WSJ on their e-readers. As for the iPhone app itself, as PC World points out, it’s very similar in style to that of The New York Times, which also has a free app. The WSJ‘s app, though, prominently features videos and podcasts. One thing that’s missing: a search function. It does, however, include the other parts of the WSJ Digital Network like Barron’s and AllThingsD.

Staci adds: It’s all about marketing and models. By making it free to start, Dow Jones gets to work out the kinks without irking paid subs and gets to market it beyond those who would pay. Eventually, I expect it to follow Major League Baseball and others in offering a free version with some access—WSJ for the casual fan, call it—and a full subscription version. The Kindle iPhone app doesn’t include access to periodical subscriptions. I also won’t be surprised if the New York Times follows suit; it, too, has had success with Kindle subscriptions.

• @ Cable Show: News Corp.‘s Murdoch: NYT Would Do ‘Fairly Well’ With WSJ.com Pay Model
• The WSJ’s Kindle Kinks