Very interesting news that I'd like to read more about and try out.  However, I just wonder whether the criticism from (say) @Derick Bailey and @Scott Koon is a little misplaced.  Surely Typescript is not so much something that will "ruin the language", but rather more of a development tool that's layered over Javascript, and even then only in the context of an IDE.  I think it's fairly clear that Javascript itself remains unaffected.