My advice to everyone is to keep your expectations low. Nintendo's obviously planning something, but if you don't create unrealistic expectations in your head beforehand, I'm sure you'll be pleasantly surprised. Otherwise...
Personally, I'm unsure what to expect because there are two conferences in two separate regions. Wii Music and Animal Crossing will likely show up in both of them, but Japan already has Fire Emblem DS, Fatal Frame IV, and Disaster, while North America does not, so those won't even be mentioned in Japan (is that why NA's is a two-day event?).
Taking a stab at this, I'll posit that Nintendo will unveil part of the early '09 lineup (one or two games, perhaps?), and that third-parties will get a bit of attention. But I'm not even sure about that modest assumption...







