Funnily enough, with this being a Nintendo console, it's only affecting a handful of games, though they do include retail disc based titles and those found on WiiWare.
- Animal Crossing: Let's Go to the City
- Battalion Wars 2
- Boom Street
- Dr. Mario & Germ Buster
- Dr. Mario Demo
- Endless Ocean
- Endless Ocean 2: Adventures of the Deep
- Excitebike World Challenge
- Mario Kart Wii
- Mario Sports Mix
- Mario Strikers Charged Football
- Pokémon Battle Revolution
- Samurai Warriors 3
- Sin & Punishment: Successor of the Skies
- Super Smash Bros. Brawl
- The Last Story
- ThruSpace™ High Velocity 3D Puzzle
- Trauma Center New Blood
- WarioWare: Do It Yourself Showcase
- Wii Chess
The big hit though, is being taken by Nintendo DS and DSi owners, who are losing the online functionality for a lot of games, including all of the old Pokemon titles. That's everything from Heartgold and Diamond, right through to Black/White 2.
Other series losing out include every online enabled Professor Layton game, Animal Crossing: Wild World and the Mario vs Donkey Kong games.
Nintendo isn't killing the online usage of the Wii though, just the game servers. You'll still be able to use your Wii to watch Netflix, buy games, browse the internet or watch Youtube etc.
This seems a bit premature, considering companies like Microsoft have continued supporting older consoles for a couple of years after their end of life. Could this be Nintendo trying to force Wii customers onto its still poorly selling Wii U?
For the full breakdown, read the Nintendo notice here.