The XBOX can do 1080i as well. I would like to be optomistic as well by saying the Wii can do 720p. I am afraid that the hardware isn't designed to do it. I think they are gearing up for the next generation, and the majority of the processing power the unit has is going towards reading the truely amazing remote control, and for the online interactive things they have yet to devolpe, or release. There are pages of channels that are left blank for the future. I think that Nintendo is more concerned about making the unit really fun and innovative, over the idea's of having a True HD output.
I would love to see at least 720p, but I would rather more options for my gaming experience online than a few extra lines of resolution.
Just my $.02