If only the 3DS had a light the size of the Wii's to notify you of new StreetPass and SpotPass notifications.
The Nintendo Channel has been updated, so make sure to go to the Wii Shop Channel to download the update for it. It is not a firmware update. The message says this update is supposed to allow you to check out 3DS information easier. What that entails, I'm not sure yet. I'll update in a minute.
UPDATE: As I figured, nothing major. Upon start-up you'll be greeted by a wall of 3DS. Four pages of 3DS walls. Under the search function, you'll see two(?) new additions; a 3DS category and now the Virtual Console specifies that it's the Wii version. You'll also see that the latest Nintendo Week finally went live, featuring the 3DS.