From Monday, February 25, 2013 11:00 PM
– Tuesday, February 26, 2013 5:00 PM Pacific Time

Affected Services:
Nintendo DS
Network Services
Pokémon Black Version
Pokémon White Version
Pokémon Black Version 2
Pokémon White Version 2

From Monday, February 25, 2013 4:00 PM
– Monday, February 25, 2013 5:00 PM Pacific Time

Affected Services:
Wii U
Match Making, Ranking, etc.
NINJA GAIDEN™ 3: Razor’s Edge
WARRIORS OROCHI® 3 Hyper

*During the emergency maintenance, parts of the affected services
may be intermittently unavailable.

On a little side note, I am not too sure if “Emergency” maintenance is a good word for what they do. Emergency means panic and I am sure this is just some routine maintenance…I hope.