According to The Wall Street Journal, the federal antitrust probe looking into alleged anti-competitive practices by Apple has been extended to include an investigation of Apple’s recently announced iAd service. Citing “people familiar with the matter” (natch), the WSJ reports that both the Department of Justice and Federal Trade Commission are taking a close look at Apple’s decision to prohibit developers from extrapolating analytical data from users devices. The main concern is that Apple will effectively be able to lock out competing advertising services from the iPhone OS by making it difficult for advertisers to properly target their ads. The most recent version of the iPhone developers agreement makes it clear in section 3.3.9 that “The use of third-party software in Your Application to collect and send Device Data to a third party for processing or analysis is expressly prohibited.” Several anonymous iPhone developers as well as at least one AdMob employee were said to have discussed the matter with the FTC, as was a wireless advertising executive who was approached by the FTC in its quest to learn about what implications, if any, section 3.3.9 will have on the wireless advertising industry. At this point in time there is no guarantee Apple will actually be rung up in an antitrust suit, but the fact alone that the government is keeping such close tabs is surely not a good sign for the Cupertino company.