It's emerged that Nintendo is planning wide-reaching "emergency maintenance" in both North America and Europe, which is likely to include other PAL territories. This maintenance is running simultaneously and in a few windows in both regions, with the greatest peak time impact being to the Wii U, Wii, 3DS and DS download stores on Monday afternoon/evening in North America, though due to time zones this is occurring at late hours in Europe.
Details of what services are down and when is below, and we've added the UK times (in brackets) to the U.S. pacific time details.
From Monday, January 28, 2013 11:00 PM - Tuesday, January 29, 2013 5:00 PM Pacific Time
(From (approx.) Tuesday, 29 January 2013 07:00 to Wednesday, 30 January 2013 01:00 UK time)
Pokémon Black Version
Pokémon White Version
Pokémon Black Version 2
Pokémon White Version 2
From Monday, January 28, 2013 5:00 PM - Monday, January 28, 2013 6:00 PM Pacific Time
(From (approx.) Tuesday, 29 January 2013 01:00 to Tuesday, 29 January 2013 02:00 UK time)
Match Making, Ranking, etc.
Warriors Orochi 3 Hyper
From Monday, January 28, 2013 12:00 PM - Monday, January 28, 2013 5:00 PM Pacific Time
(From (approx.) Monday, 28 January 2013 20:00 to Tuesday, 29 January 2013 01:00 UK time)
Wii Shopping Channel
Nintendo DSi Shop
As this is affecting older retail titles as well as the Wii and DSi Shops, we are doubtful that this maintenance is anything particularly exciting in terms of functionality. Whatever the reasons, we're sure that we can survive a few hours without eShop access.