Don't get excited or anything; there's no indication anything spectacular is happening, just be aware that you won't be able to access the eShop for most of Thursday, or online play for Pokémon X/Y today.
Before you panic and try to preorder it, know that it's just the software and collectable blue shell, not a Wii U bundle. No news yet as to whether or not North America will have a similar special edition version of the game.
As of May 20th, you'll no longer be able to access the online mode for your Wii or Nintendo DS. This means no more online Mario Kart DS racing, and no more Super Smash Brothers Brawl online. See a full list of affected software in the via above.