The announcement is super early, but from what we can tell, Dragon Quest creator Yuji Horii "accidentally" said "We're developing Dragon Quest X on the Wii." Satoru Iwata then went on stage and said "Thank you very much for developing Dragon Quest X on the Wii!" Horii protested and said something to the effect of "Let's introduce Dragon Quest IX first!"
Thanks for making the internet explode with your banter, guys! Reuters has confirmed the announcement as well, and they're, like, respectable. (And their writer was probably there.)