FCC has begun an investigation into the matter that involves Apple's rejection of the Google Voice iPhone app. In its letters to AT&T, Apple, and Google, the Commission asked each party to clarify exactly what happened and why the application was blocked from the iTunes App Store. FCC Chairman Julius Genachowski said, "Recent news reports raise questions about practices in the mobile marketplace. The Wireless Bureau's inquiry letters to these companies about their practices reflect the Commission's proactive approach to getting the facts and data necessary to make the best policy decisions on behalf of the American people."

More info: FCC's letter to Apple | FCC's letter to AT&T | FCC's letter to Google