Well, seeing as the patch is a small software app, and you can use that same app to turn OFF the patch, I can't see how Apple could tell you you're voiding your warranty (and if you turn it off, they won't know you even did it). Personally, I've never seen any documentation that says messing with Openfirmware voids your warranty. The problem is, none of us wants to be seen as pushing a non Apple approved hack to a machine that's purposely got that feature turned off. Still, I did it to my old iBook, and I know folks who've done it...only one guy ever had a problem, and that was due to his iBook NOT being supported by the hack.