A few days ago, the Wii and DSi Shops went down without warning. While users cannot purchase any new games from the storefronts, they can redownload any titles they have already purchased through the storefronts.
Unfortunately, both stores have been offline for a while now, with Nintendo just now commenting on the situation in an email to Kotaku:
“The Wii Shop Channel and Nintendo DSi Shop are currently undergoing maintenance. We will provide an update at a later date.”
Nintendo did not provide any further comment on the outage. Hopefully the storefronts come back up soon!