This week, is a throw back to a previous episode that was in Naruto some time ago. I suppose this was done so people who do not follow the series very well can finally get an answer to that age old question back when Naruto first started. Edit: It has come to my attention that this episode is considered to be a canon/special episode. Personally I see it as filler despite supplementing the story somewhat.
Which means that... Next week, Episode 470 is officially canon, so with the big secret revealed. We can now put this to bed. For good.