Yesterday, Nintendo chose to take down the eShop on both the Wii U and Nintendo 3DS for maintenance as a result of the new system load and the terrible problems caused by the launch of Pokemon Bank and Poke Transporter in Japan. Now, Nintendo has announced that the shop must be taken down once again for more maintenance.
Just like yesterday, the eShop will be taken down at 4 pm EST, but this time there was no specific end time given. However, the European eShop is said to also be closing, this time for 12 hours as before, so you would assume that the US eShop is likely going to be closed for the same period of time.
As a result, if you require any eShop purchases today, get on there and buy something in the next 45 minutes or so, or you will have to wait until tomorrow.