Re: json.el - JavaScript Object Notation parser / generator for Emacs Lisp

[Richard Stallman]

    > If a lot of people start wanting this facility, then it would be good
    > to include it in Emacs. Please let me know if that happens.

    I know of several libraries/tools which use json.el, including
    augment.el, a facebook api client, rcov.el, and at least one twitter api
    client. Additionally, I know of at least one library, twit.el, whose
    author avoided using json.el solely because it isn't included in Emacs.

That sounds like plenty of usage.