http://biz.gamedaily.com/industry/feature/?id=12852
Quote"Let's say your Wii is connected to the Internet in a mode that allows activation on a 24-hour basis. This would allow Nintendo to send monthly promotional demos for the DS, during the night, to the Wii consoles in each household. Users would wake up each morning, find the LED lamp on their Wii flashing, and know that Nintendo has sent them something," Iwata explained. "They would then be able to download the promotional demo from their Wii's to their Nintendo DS's. This will, of course, be possible in gaming stores too, but I think users will enjoy being able to do this within their homes. The key merit here is having promotional material delivered to your home, instead of having to go collect it yourself."
Let's take this a step farther. Let's say you have a DS game that involves customization or collecting things (Animal Crossing, Pokemon, any RPG or adventure really). You could turn it on in your living room and your Wii would say "Oh hey, you just got the new RPG game. Cool." then a few days later, you turn on your Wii and get a nice little message that says "Hey, thanks for buying our new RPG game, we hope you like it. Here's a Level 20 foam cowboy hat. Turn on your DS and we'll download/unlock it for you."
Take that Sony.