We've written about the whole GV Mobile app rejection before but the tech soap opera continues. According to the WSJ article, it's clear now that GV Mobile app was rejected because "Apple believed the application duplicated the core dialer functionality of the iPhone." This information came for the Apple letter sent to Google and it's in conflict with their prior statements made during the FCC investigation. Apple told FCC that the app was not being rejected and that they were still studying it.
Well, while the whole mess is being sorted out, we still can download GV Mobile via Cydia for jailbroken devices.
Update: As per Silicon Alley Insider Response from Apple: “We do not agree with all of the statements made by Google in their FCC letter. Apple has not rejected the Google Voice application and we continue to discuss it with Google.”

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That’s not accurate. Apple said that it hadn’t been rejected and they were still evaluating it, not that it wouldn’t eventually be rejected.
http://wireless.fcc.gov/releases/9182009_Google_Filing_iPhone.pdf (google learned from apple via Paul Schiller that app is rejected on July 7th)
Apple response to FCC is dated July 31
http://www.apple.com/hotnews/apple-answers-fcc-questions/ (App is not rejected we are still studying it)
Information from Apple does not match information from Google, someone is not telling the truth.