Naturally I applaud languagehat's defense of the noble form y'all:
[...]y'all is a particularly bad example to cast stones at, since English badly needs a second-person plural form, and that's a convenient and (to my mind) attractive one. I use it frequently.
Of course. I use it all the time, myself. Ever since the demise of thou and its cases, English has been walking around immodestly with no proper second person plural. (Note to ignorant Yankees: one does not use "y'all" to address an individual.) Unfortunately, though "y'all" neatly bumps "you" into the second person singular slot and takes on its former pluralizing duties, the second person in English has not yet reinstated the second person singular formal duties of the second person plural. Hence I am still bereft of a form to distance myself from overly familiar whippersnappers and telemarketers (who invariably mispronounce my first name). By the way, to certain foreign bloggers - and some northeasterners, for that matter - who persist in believing that the use of "y'all" is a veritable scarlet syllable signifying, inter alia, ignorance, racism, theocratic sympathies, and in general, illiberal tendencies of satanic proportions, I say: screw you and your blinkered parochialism. May you spend eternity at a cocktail party in hell sweating the imaginary nuances - for a native speaker of American English, anyway - of person and purpose for "shall" and "will".
While I'm on the subject of existing usage, allow me a little aside on non-existing usage. I know that children, when they are beginning to master spoken language, speak, quite rationally, according to the logic of grammar, not "correctly". I was charmed at my daughter's constant use, when she began to speak, of the construction "amn't I?". And I had to wonder why English speakers do not say "amn't I". People tend, if they go near that interrogative construction at all, to say "aren't I", which makes no sense at all. "I are"? Feh. (Does "ain't" fit in here somewhere?) Could some linguistically-informed person enlighten me on the reasons for the absence of the logical and easily pronounce-able form "amn't I" from standard speech? I'm correct in my grammatical logic, amn't I?