There's a new exciting debate over the ES4 proposal which is available online at:
http://www.ecmascript.org/es4/spec/overview.pdf

The reason?

Besides some people arguing over the complexity and possibly over-engineering of the new language, there are major corporate implications. Microsoft may not want to implement ES4 and it's quite unclear what their plans are with IE8. Does it make sense for Mozilla, Opera and Safari to implement a new javascript engine if Microsoft (IE) doesn't follow? Probably not.

But some might say, implement the standard and let Microsoft (possibly) follow up later. The problem is that for developers (scenario: IE doesn't implement the standard), we are stuck in the same interoperability mess when building web applications. Hack and hack after hack to support either buggy or non-existing implementations! It's further unclear if Microsoft has any interest for javascript to succeed in the long run and become a driving force in the success of web applications. The corporate strategy of Microsoft is not transparent with regards to their web technology such as Silverlight (brings .NET to the browser). In short, business is getting in the way of collaboration and benefiting the end users. On the other end, it's unclear how Adobe and Mozilla are related and if the donation of actionscript to Mozilla puts Firefox at an advantage to implement this proposed standard compared other browsers (IE, opera etc...).

Open Standards

No doubt, the solution is for browser vendors to actively implement and support a javascript engine according to the same standards. It will be interesting to see how this unfolds, important communication and decisions are ahead with regards to new web standards.

On a personal note, I like some parts of the proposed standard though I believe there's some over engineering with the type hinting. I am a strong fan of interfaces and classes.