I know Facebook has some D advocates, but D doesn't seem to be too popular among the programmers I know. I haven't looked too deeply at it myself, but it seems to be a language more interested in taking the job of Rust and C, rather than the job of Python and Ruby. So there is no reason Facebook can't pursue both languages as a company.
The two languages seem to diverge when it comes to the fact that Walter Bright seems to like to write both expressive and high-performance code (meaning, at the same time). That kind of philosophy tends to lead to iterators, generators[2] etc. which Go seems to look at as superfluous -- just write a for loop, more or less.
[1] Write C++ for the particular software that they make, anyway.
[2] Or whatever the equivalent is in D.
Well done daaku :)
