There haven't been too many iPhone applications that prompted a federal investigation, but one that did--Google Voice--is now finally available in the App Store.
Google announced the availability of the official app today, nearly a year and a half after it first submitted Google Voice to Apple. Apple's reluctance to approve Google Voice--Google claimed that Apple actually rejected the app while Apple said it was evaluating it--led to an investigation by the Federal Communications Commission into Apple's App Store approval policies, and a deepening of the rift between the two formerly close partners.
Apple relaxed those rules in September, which has led to a number of formerly banned applications making their way onto iOS devices.. Google Voice lets users give out one phone number that can ring multiple phones, and transcribes voice mails. A Web version has been available for the iPhone since January.
Google said iOS users have to be running version 3.1 or later, and it's only available in the U.S. at the moment.