Apple have publicly answered the queries from the FCC around Google Voice.

Highlights:

Apple is acting alone and has not consulted with AT&T about whether or not to approve the Google Voice application. No contractual conditions or non-contractual understandings with AT&T have been a factor in Apple’s decision-making process in this matter.

The application has not been approved because, as submitted for review, it appears to alter the iPhone’s distinctive user experience by replacing the iPhone’s core mobile telephone functionality and Apple user interface with its own user interface for telephone calls, text messaging and voicemail.