So far there’s been no news on Microsoft’s reaction to “open source” being officially recognized by the arbiters of the English language.
“Open source” is now officially a word according to Merriam-Webster, according to my good friends at Ars Technica. Actually, I don’t know anybody at Ars Technica, but whenever you’re stealing news from another news source, you’re traditionally allowed to refer to everyone who works there as “my good friends.” The theory is that if they think you’re a friend of theirs, they won’t sue you.