WiiWare's been around since the system first launched. They're basically little programs you can download for the system like the Weather Channel or Everyone Votes thing.
I noticed my system was flashing last night (a notification that you received mail), so I check it out when I got home today. It was a notification for the new channel. Seems cool enough. It's mostly videos of games, but there's also the mention of the DS downloads on there. Ninja Gaiden is on the list, so I'm going to have to give that a try at some point.