I think many of us knew this was coming! Earlier it would have been a nice relationship but when Google came out with Android mobile platform and the future plans for the Chrome OS, an Operating system for desktops, Schmidt's seat on the board was getting hotter. Even earlier to resignation, Schmidt had to leave the room when iPhone was discussed.
But I wonder Google Voice too had some role to play as it seems Google informed FCC about the Google Voice App Rejection.
Anyway, AT&T has claimed innocence in the Google Voice Saga saying it had no role in rejecting iPhone Apps.
Apple's Press Release
CUPERTINO, California—August 3, 2009—Apple® today announced that Dr. Eric Schmidt, chief executive officer of Google, is resigning from Apple’s Board of Directors, a position he has held since August 2006.
“Eric has been an excellent Board member for Apple, investing his valuable time, talent, passion and wisdom to help make Apple successful,” said Steve Jobs, Apple’s CEO. “Unfortunately, as Google enters more of Apple’s core businesses, with Android and now Chrome OS, Eric’s effectiveness as an Apple Board member will be significantly diminished, since he will have to recuse himself from even larger portions of our meetings due to potential conflicts of interest. Therefore, we have mutually decided that now is the right time for Eric to resign his position on Apple’s Board.”Complete press release is here.