Last year I left a laptop at my parents' house with Linux Ubuntu installed. I had it hooked up to their TV for streaming movies.
So, this week he gives me a call and tells me that his Windows laptop battery died and he's been using my Ubuntu laptop. He tells me about how he found the Libre Office spreadsheet and he's been filling out his work documents (he works in high-end custom home construction) with it and transmitting it with Google Docs.
Then he tells me that he was able to add their house printer and print his docs from the machine using the instructions from Ubuntu's help system.
I was pretty much floored. My parents are NOT technical people. I offered to get him a Windows license for the machine but he said that it's working fine for him.
People make jokes about the "year of desktop Linux" but if my dad, without calling me ONCE, can use Linux productively to get things done, then, in my opinion, Microsoft is in trouble. As far as I'm concerned, their claim to usability in the PC OS world is dying.
Maybe this doesn't mean a whole lot in the big picture, but Linux has cost Microsoft at least one end-user license for an average computer user. For my family, I'm not sure how else you define a "year of Linux desktop."
Rather, Microsoft is (or was, in the pre-post-PC world) everywhere because of (a) licensing stitch-ups with hardware vendors and (b) network externalities: get into Corporate IT departments with Office, then people will want (or need) to use the same OS at home, and then you can strong-arm hardware vendors into signing exclusive Windows-only-on-our-PCs licensing deals, which in turn convinces Corporate IT that there's no viable alternative to a Windows-only ecosystem ...
Arguments about whether or not Linux is fit for desktop use by non-technical users miss the point: Windows' monopoly status was a virtuous circle (for a value of "virtuous" that approximates to "in the interests of MSFTs shareholders and provides job security for MCSEs") until the wheels fell off when confronted with an even bigger ecosystem that came out of nowhere. Which is the magic rabbit Apple pulled out of a hat with the iPad, and Google seeks to emulate with Android.
The desktop is now irrelevant -- less than 10% of computing devices people use are desktops or laptops: it's all gone mobile frighteningly fast -- but for what it's worth, Linux won. Because the winning Linux desktop is actually a phonetop or tablet environment: Android.