In reply to Mel fisher.

@Mel,

1. It seems (based on what I read on the support forums of wp.com) like the admin side of wp.com was for some time written in JS. This is "written" and not "rewritten" as it has nothing to do with the internal workings of wordpress, they just created an interface between the JS app they have written and the wordpress core code.

2. No. by now wordpress is too old and has too much of eco system depending on the specific ways it works to be rewritten in any significant way, any attempt to do that will be more like developing a new CMS from scratch. There is also no advantage in doing so as you still need something to run on the server, and whatever difficulties there are in developing server software, they will not go away just by changing the language being used to do it. And it will have zero advantage to the user.

wordpress already has two JS apps, the media uploader and the costumiser. You might see more functionality written that way, but no full rewrite.