Let's vote.

It's a difficult question, if week 4 is higer than week 3 (which is higer than week 2)...holy god! I knew the game was gonna reaching 3 millions but I didn't think that fast...

Anyway I'm gonna saying lower than both week 3 and 4, but without a specific reason, just I think it will sell 350-400k, but near 600k seems too much IMO in the 4th week of a game. even if it's a 2d Mario.

Wow I used to feel so certain on how this game will sell in Japan, but really I have no earthly idea. So I won't embarrass myself haha. I want to say lower than week 3 and I feel that's what will happen but really I can't say that strong enough or definitely haha.

I'll say higher, because right now we're still having the run-up to the big New Year's holiday in Japan. Sales should continue to be stellar either way.

Pretty much what Zucas said

it'll be lower, usually nintendo sales go down that week. The week after that is actually usually bigger. It wouldn't surprise me if it went down something like 100k next week, then went up a little or stayed flat the next.

I choose higher cause I'm on fire!

Everyone expected Week3 to be lower than Week2. Everyone was wrong.
I think nobody can confidently say Week4 will no be a surprise.

I picked higher due to last holiday shopping.

yeah but it's not that surprising, it's the biggest week of the year for nintendo consoles every year.  Hardware sales are usually up 50% over the previous week, so a game that people buy when they buy the system increasing in sales isn't that surprising.  Next week hardware sales will be down.   It's not impossible but it's unlikely.

http://vgchartz.com/swlaunch.php?reg1=Japan&game1=New+Super+Mario+Bros.+Wii+-+Wii[35076]&reg2=America&game2=New+Super+Mario+Bros.+Wii+-+Wii[35076]&reg3=Others&game3=New+Super+Mario+Bros.+Wii+-+Wii[35076]&weeks=5&weekly=1

And the forth week preview is quite interesting, too. A chance at beating week3!