An overview paper describing ECMAScript 4 has been added to the ECMAScript site. It was recently announced on the mailing list:
I'm pleased to present you with an overview paper describing ES4 as the language currently stands. TG1 is no longer accepting proposals, we're working on the ES4 reference implementation, and we're expecting the standard to be finished in October 2008.
This paper is not a spec, it is *just* a detailed overview. Some features may be cut, others may be changed, and numerous details remain to be worked out, but by and large this is what TG1 expects the language to look like. Your comments on the paper are very much welcome. Please send bug reports directly to me, everything else to the list.