http://www.rarewarecentral.com/diddy-kong-pilot
http://www.rarewarecentral.com/beta-games
Coming November 5th.  

My friend bought the cart from a collector a while back.  It's almost exactly like Banjo-Pilot's retail version, except the DK characters turned into Banjo-Kazooie characters, a few additional graphics for the level backgrounds and object, and that's about it.  Here's some footage:

http://www.youtube.com/watch?v=sg7SYh1lWqQ
http://www.youtube.com/watch?v=Ug5EwTSFt10
http://www.youtube.com/watch?v=4fMo-5IPrU4