I would say something like; "Oh, yay! I've been waiting for this!"

 But in realtiy it's more like; "Took ya long enough you... You... Grr..."

'When Activision previously announced that the Wii version of Guitar Hero: World Tour would have downloadable songs, some people played the skeptic card and everyone else went "Well, how will you do it?". Today, that question was answered. In a new interview, CEO of Vicarious Visions, Karthik Bala, revealed the method for the downloadable content would be the SD card. Guitar Hero World Tour will be the first Wii game to have an in-game store and offer songs for purchase (even with previews, too.).

New songs will be added to the store on a regular basis. Songs will not only be able to be saved to the Wii's internal memory, but also the SD cards where it will form a section known as the "Rock Archive". Don't fret either because the music will "sound great" too.'

Well that helps considerably. And I don't really see why the SD card couldn't have been used in past games... Surely if MP3s can be played from it so can other things...?

Source.