Talking to Japanese business publication (Nikkei Business), Iwata distances the Wii console from the rest of the pack, stating the Wii is not an extension of a previous incanation and therefore it cannot be classed as 'next-gen'.
Full story:
http://www.gamernode.com/Wii/News_759/index.html
"Nintendo is not working on a next-generation console. ‘Next-generation' implies that the console is an extension of previous installments. We believe that extending our current line will not lead to larger markets and could possibly even lead to smaller markets."
Full story:
http://www.gamernode.com/Wii/News_759/index.html