I'm making good progress on the multiplayer demo for Mt. Hildar.  It's on track to still be done by the end of the year.  So far I have 6 screen in place and should have a few more tonight.  Screens will be similar to old Zelda games where they have no scrolling, and they are each treated as individual regions.  Inside each screen, chatting will be separate, like one unique chatroom per screen.  I'll write a blog about it at DSiPaint.com tonight.