According to a Famitsu report, Wii U will be region-locked. This will likely be the case given how Nintendo approached the situation with the Wii and 3DS.
The publication wrote in a recent issue:
“What can be played on the Wii U is restricted by a region-lock feature; software not sold in the same region cannot be played.”
Alright Nintendo… this means you can’t take forever to localize games like Xenoblade!
Thanks to 4Him for the tip.