Over the past few months, various whispers have repeated rumors of a PowerPC 975 processor which is meant to be a successor to the PowerPC 970 (G5).
Unfortunately, these rumors have come from consistently unreliable sources. As a result, the existence of a "PowerPC 975" remains in question.
Due to the nature of rumors, the information has also been repeated on numerous websites and message boards.
At this time, however, there appears to be no reliable information that the PowerPC 975 is an actual planned product. Instead, it should be regarded as a possible invention of the rumor world until further confirmation is provided.