The DSi should do good business! And where there's good business, there's Activision, ready to exploit that business, in this case with a downloadable DSi title.
That title is Mixed Messages, developed by port & handheld specialists Vicarious Visions. It's a party game for 2 to 21 players, and works a little bit like Pictionary, with players drawing something before passing the DSi on to somebody else to draw something else.
It's available now for 500 Nintendo Points. Oh, and it's the first third-party downloadable title for the handheld, for what that's worth.