Play-Nintendo has an article up with some quotes from the Rare Scribes pages that mention two things. First, Rare/Microsoft hasn't dismissed the idea of Banjo-Kazooie showing up on Wii's Virtual Console. Second, Diddy Kong Racing isn't clearly Nintendo's.
SPOnG has an article up where Reggie Fils-Aime, President of Nintendo of America, said "We know that there are a lot of fans from Microsoft and Xbox because they call us constantly trying to get product.
Gameblog The Pensive Gamer speculates:
"Why would Microsoft let Nintendo put Banjo-Kazooie on the Wii? Seeing the two articles made me think the idea is a negotiating tactic. Microsoft would love to see a Nintendo property on their console. If Diddy Kong Racing isn't clearly Nintendo's (and this could be due to an old contract between Rare and Nintendo) it could be the perfect game to grab. Microsoft could offer Banjo-Kazooie to smooth out even the potential of a legal situation."