RedOctance have stated their stance on downloadable content for Guitar Hero III Wii.

An email response from RedOctane customer support gave the indication of their position as far as downloadable content on Wii:

Hello,

Thank you for writing us.
Downloadable content for the Wii is something we are working very hard on getting in place for the new year. There is no definite timetable in place but we are hoping it will be soon.

Regards,

RedOctane Customer Support


Downloadable content without a hard drive can prove somewhat troublesome so it's probably time Nintendo announced the hard drive we've all been waiting for since day one...