A QA tester for Call of Duty: Black Ops 2 lists duties that include testing the game's PS3 & Wii U versions.
Randall Herman, a quality assurance tester at Treyarch (the developers currently making Black Ops 2), updated his LinkedIn Profile to include "QA testing on PS3 and Wii U" under his duties with the game. The full listing can be seen below, we have also added a screenshot of the profile in case it gets taken down.
This is in line with earlier news about Treyarch studio head, Mark Lamia, hinting at the possibility of a Wii U version of Black Ops II in an interview with PressFire. However, despite previous and current evidence for the existence of this game, Activision has not technically announced the existence of a Wii U version of Call of Duty: Black Ops 2.