Kotaku - 659 people are playing standard multiplayer and 68 people are playing Zombies mode on Wii U. More than last week.
For comparison, there are 511,529 people playing standard multiplayer and 124,321 people playing Zombies mode in Black Ops II on Xbox 360.
Of course, it's not fair to directly compare a console that launched last week with a console that's been around for six years. So let's do some math.