Might be interested in this but most likely not at full price. Cos I bet it's gonna be like 80 bucks or something. Wonder if Rock Band's gonna have more compatibility with the old instruments. I only have the GH:WT stuff which does work with last gen Rock Band.
They announced a price, and it's $100 for game and guitar.
The new Rock Band is talking about trying for compatibility with old instruments, but who really knows until they announce some more. My personal feeling is that I don't think they would have talked that much about it if they don't have something at least significantly in the works (like a dongle or something to make the old stuff work).