It's still fairly accurate. A cursory read through it (I read it once several years ago) and I don't see anything that needs updating, except maybe the books section. Of course, I haven't read much dead tree documentation for JavaScript, so I can't really comment on that aspect.
Since the article was written, a few things were added that are handy, but not expounded upon in the article: we've gone from 1.4 to 1.8.1, and added some helpful things like array helpers, iterators, and so forth. Not much else has changed, though - for instance, you can and probably always will be able to accidentally save a variable to the global stack if you assign a value to it without declaring it.
Since the article was written, a few things were added that are handy, but not expounded upon in the article: we've gone from 1.4 to 1.8.1, and added some helpful things like array helpers, iterators, and so forth. Not much else has changed, though - for instance, you can and probably always will be able to accidentally save a variable to the global stack if you assign a value to it without declaring it.