This post goes out to whoever in Microsoft might be able to shed some light on the subject:
When, if at all, can we expect to see support for E4X in JScript[.NET]?
My main reason for asking is because Mozilla recently added support for it to their ECMAScript implementation and I can already see the same thing that happened when people wrote code for proprietary DOM implementations is going to start happening again. This time though, it’s going to be E4X code not working in IE. I realize C-Omega should eventually result in similar features being added to C# 3.0, but that’s no reason for JScript.NET not to run with E4X as well. The problem is though, IE uses the ActiveScripting version (JScript), so it’s more important for that version to be updated to support the spec since that’s the implementation that matters when it comes to every day web browsing.