I thought the M# name was completely made up during speculation, but it does indeed appear in the job posting [0] (you have to click the Job ID target 837005 to see the text) cited in this [1] reddit comment. (Edit: it's not entirely clear if M# and the language being discussed are the exact same language. I would assume they share some ideas, at least. Microsoft can't be _that_ fragmented, I would hope.)

The discussion thread on LtU hasn't pick up much steam, probably due to mid-holiday lull. I'm still a but confused about Charles Torre's comments re: HN/Reddit speculation. D and Rust were brought up in the the main source blog post [2], not by random speculators. He's right that we don't have "many of the details required to make intelligent comparisons", which is a shame. Charles also states in the comment

> "Joe mentioned his desire for openness for the technology (as in open source AND open communication/transparency). That we can have this conversation in the open means Microsoft is turning a corner vis a vis transparency. I hope this trend continues."

Let's see it then. Until then, there isn't much more to say.

[0] https://careers.microsoft.com/resumepreview.aspx?aid=111551

[1] http://www.reddit.com/r/programming/comments/1tvic1/the_micr...

[2] http://joeduffyblog.com/2013/12/27/csharp-for-systems-progra...

Edit: Tracing the various sources for parts of the speculation is interesting on its own. The various projects being cited show that Microsoft has spent a long time in this research space. I remember hearing about the Singularity OS [3] project at Microsoft, and wondering what we would see come out of it.

[3] https://research.microsoft.com/en-us/projects/singularity/