There has been much huffing and puffing about the inclusion of such words as thang, blingy and tik (methamphetamine) in the latest Collins "official" list of Scrabble words, but of course this is a matter of total indifference except to those daft enough to play Scrabble with people who take the game so seriously that they will pay £16.99 for the book.
Real dictionaries have detailed criteria for the acceptance of new words rather than depending on mere editorial whim. The realest of them all, the OED, accepted for inclusion this year (for example) LOL, couch surfer, fnarr fnarr and OMG (about time too; this one's nearly a hundred years old).
But not yet innit. This, though, is only a question of time, for it is unquestionably in sufficiently wide and probably permanent currency to warrant inclusion, and certainly fills a lacuna in our language: we have no invariant tag other than the crude eh? or huh? enabling us to ask for the agreement of the listener, and have to use a huge number (pity the poor foreign student of English!) of clumsy phrases like don't you? or shouldn't we?. But innit, which is a rather neat contraction of Is it not so?, can be used in any context, being the equivalent of n'est ce pas?, ¿verdad? or nicht wahr?
So we should all start using it now, without waiting for the OED to catch up, innit?