In a recent Q&A session, RedOctane cofounder Charles Huang confirmed the existence of Guitar Hero III DS. Huang did not reveal any further details, but did say the game will play "probably unlike any other DS game that has come out."
And what about a custom DS peripheral?
[blockquote2]That is definitely one of the options we're exploring. The DS peripheral is very intriguing to us. It's an integral part of the Guitar Hero experience, so as much as possible, we would like to keep it within the experience as long as it makes sense and it plays well.[/blockquote2]
He went on to say that the peripheral will be affordable and fit mass market needs. No idea what this "peripheral" will be, a mini-guitar, perhaps?
Q&A: RedOctane cofounder Charles Huang [CNet]