According to the March Issue Of Nintendo power it is. Here is a “supposed” excerpt for the issue:

– Kingdom hearts 3 Wii exclusive, developed and published by square-enix.
– Tetsuya Nomura is the game director.
– Yoko Shimomura composer.
– Direct sequel to KH3, but also will reveal interesting things about chains of memories.
– Sora main character, a new misterious girls is also one of the main characters
– combat system vastly improved, every attack looks “sick”, uses Wii-Remote in a very intuitive way
– Best looking Wii game, uses normal mapping far more than Konami’s dewey’s adventure, the animations are incredible and the art directon is a little less “kiddie”
– Winter 2008 release

 Update: As soon as this popped up this rumor has been proven false. the people over at nintendo-revolution , contacted Future US, publishers of NP.  Future US has insured them that this story was false.  It was fun while it lasted.