Yeah it's posible upscale Wii games with better graphics, some upscaler around can do the miracle. But is expensive and only Nyko upscaler is compatible with Wii by component cables and ofter great result at low cost.
Nyko posible talk to Nintendo to license this product and will come with a Wii firmware update to confirm compatibility with games. And mach the correct resolution of your HDTV. (Avoid flickering).
It will launch the summer of 2007.
What is a upscaler?
You can find any at Google. Your best friend!