Via Chris Sells comes this cryptic message from Microsoft's Doug Purdy:

We are looking for developers/testers to build a tool that I will roughly describe as "Emacs.Net".

No more details than that, but it should be enough to get your brain moving in the right direction.

Which he then elaborates in comments:

Emacs is a text editor. Emacs is used to write apps (and a whole lot more) on different platforms. Emacs is hyper-extensible. More at http://en.wikipedia.org/wiki/Emacs.
Imagine if someone wanted to write something like Emacs.Net. Actually don't imagine it, it is happening.

The literal reading of the post (a clone of emacs) is too absurd to credit. As put by a commenter:

Neat, so you want to make a clone of a free, open-source, extensible text editor that is loved by millions and write your own closed-source, proprietary, extensible-with-subscription text editor of your own?

Surely not.

So what are the relevant characteristics of emacs?

1. text editor : But there are gazillions of text editors, including programming editors, on every platform already. Microsoft even has their own little system they seem to like. Can you think of any computing context in which text-editing is often soured?
2. cross-platform : But Microsoft is a Windows company. I mean, sure they develop a couple things for the Mac, but le's face it, Microsoft doesn't really support other platforms. Do they?
3. very extensible : But emacs is extended with LISP. An editor that's extended with C# or VB only is going to seem less flexible. And you can already extend VS with those languages. To really have emacs-like "hyper-extensibility," you would have to extend it using language(s) that themselves are very flexible.

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Counting against this supposition (a Silverlight-hosted text editor based on the DLR) is that I believe that Doug Purdy works in the Workflow and Windows Communication Foundation (WCF / Indigo) teams, which isn't where I would expect such an initiative to flourish.