What is nook?
And don't worry about warranty. If you got problem, just factory reset your phone or pod or pad and go to apple for problem. They don't know U jailbreaked your device and I can prove it cause I'm a jailbreak user and I fixed my pod twice.

... Nook is a tablet by Amazon, this post really doesn't belong in the osu!iPhone subforum.

In any case, it's apparently possible to get cyanogenmod 9 on your nook, which is approximately equivalent to Android 4.0 (Ice Cream Sandwich). You could then try peset's osu!droid. Theoretically speaking, that is- I don't have a Nook myself and thus haven't tried doing so.