Skeptical Optimist is completely correct in his rant. If someone's calendar doesn't capture everything that matters, that person needs to spend an extra 5 minutes of their day making sure it does.

And, I fully expect people to act as if I know how to manage my calendar and therefore appropriately schedule meetings during those times I show everyone that I'm free. Fortunately, at my company, it's rare for someone to not have this figured out yet.