This kind of thing is a pet peeve of mine, and of my wife’s. We’re both avid readers, and she’s the daughter of a teacher as well; we know how these phrases are supposed to be spelled, even if we don’t know the background of them (I never knew where “beyond the pale” actually came from until I read the article). When we see them misspelled in someone’s writing, we just have to wince.
(She hangs around FaceBook, so she winces a lot more often than I do, but I get some too… I actually saw someone write, last week, that Apple should “up the aunty” on the minimum memory size of the iPod Touch. And according to Google, he’s not the only one misspelling that phrase. You’d think that Aunty would have something to say about that.)