DigiTimes has a brief mention of the Commercial Times story that Macronix is seeing 35% of its 2006 sales come from mask ROM orders for Nintendo's upcoming Wii home console.
Mask ROMs are read-only chips used to store system software. A run of Mask ROMs has a high set-up cost but the resulting savings for manufacturing high volumes means the chips are very fiscally efficient, provided errors are not later discovered in the software that would require making an entirely new run of ROMs. It seems likely that Mask ROMs for Wii would be used for some core components of the system software while other updatable components would live on the system's onboard 512MB Flash ROM, which is rewritable.
ATi and PixArt also recently reported big orders from Nintendo for Wii's "Hollywood" graphics processor and motion-sensing processors in the Wii Remote controller, respectively.