well whats obvious is that nintendo expected to sell at least a million a month world wide (which is easily double 360 or ps3). And they expected to sell at least over a million during the christmas week (or else these machines wouldnt have been shiped to market) So from the word go Nintendo was aiming to go 2 times that of 360 or ps3.

http://vgchartz.com/hwlaunch.php?cons1=Wii®1=All&cons2=PS3®2=All&cons3=X360®3=All&weeks=156&weekly=1

Now that the console has found its feet and its prooven to be a success they are ramping up production to meet demand. It doesnt mean they didnt think there would be this much demand, they were just making safe business decisions. Nintendo is good at that, especially with their sales projections.

If they did not expect Wii's success they wouldn't release it, but they did not expect to outsell PS and Xbox so badly.

After E3 06 they new it would be big but I think after the begining of 07 when they couldn't keep the console on store shelves for any length of time(if at all) then they knew

Before E3 2006 they were set for producing only 500k Wiis per month.

After seeing it's popularity there they managed to up it to 1 million per month before launch.

As others have said.. they knew it was popular, but not this popular.

Of course they expected success with the wii. They were offering something completely different to their competitors at a lower price point.

Nintendo are wily old geezers