Microsoft's a big company, and that makes it a big target for lawsuits. We all know that. But what doesn't always sink in is how careful the company has to be.
For example, in Microsoft Official Curriculum course 10961, Automating Administration with Windows PowerShell 3.0, I have to type Windows PowerShell every single time. I've actually been using "the shell" a lot, just to break things up a bit. We all casually refer to the shell as PowerShell, but Microsoft never does. Their trademark is on Windows PowerShell, and believe it or not someone has a trademark on PowerShell. I think it's a sporting equipment manufacturer.
As I'm writing the course, I started using Windows PowerShell on first reference, and then naturally - for me, at least - used just PowerShell from then on. Nope. Had to go fix 'em all.
I mean, technically... legally... you don't trademark an entire word. You trademark it for use in a particular field. So it's theoretically possible for Microsoft to own the trademark PowerShell in the world of computer software, and another company to own the same trademark for making backpacks or ski boots or whatever. But... I get it. You gotta be careful, and it's easier just to not overlap with someone else's trademark.
Maybe they should have named it FrabulouShellâ„¢ instead, just to be really sure.