This is the kind of PR (rather than marketing) that I despise, because it is deceiving.
I mean, its annoying that it wasn't clearly stated that it was a MS article, but from the beginning I thought it was fairly clear that it was an advertisement for something, and all the Microsoft references was a pretty strong hint it was for them.
Do we know for a fact that this was a marketing tactic conceived and developed by the Marketing group at Microsoft? Versus simply these three individuals, of their own accord, wanting to show off the tools in a fun(?) way?
Does it matter? If you're showing off something that depends on your company's product then you're advertising for them, regardless of whether you're paid for it directly.
Yes, it does matter. I'd question the intentions of a marketing department very differently than I would 3 developers who appreciate a given set of tools and want to share them with other developers.
Kudos to you for noticing but! I think they should add some kind of disclosure.