Eurogamer has reported that the Nintendo Wii and DSi shops are down. The outage was initially reported as of March 16 and to date, no explanation from Nintendo has been made.
This comes on the heels of a recent announcement about the Wii U and 3DS shops and their sunset, along with a maintenance suspension of the Nintendo eShop in Russia due to the inability of accepting payments. However, while the front-end might still be down, sources claim that the servers are still up and that content can still be obtained through third party downloaders such as NUSDownloader.