Thing with Zelda is TP wasn't the Wii's title - it was adapted for the Wii to help the launch, it doesn't suprise me we are going to get another so soon.
I reckon they were probably half way through when the Wii got launched, Mario on the other hand - didn't expect that but bring it on.
But where's Pikmin 3 - come on Nintendo, it's my favourite GC franchise