I think the question is whether you find yourself confused by the fact that Apple makes FaceTime while Facebook makes Facebook (and Think makes FaceCash).
At some point, and this is why the Star Trek / Star Wars example matters, consumers realize that the prefix is generic within the scope of a given market. Telecommunications and faces overlap a lot these days.
Personally I would think that FaceTime and FaceCash were made by Facebook Inc. (As I had actually never heard of either of those).
I also thought that Star Trek and Star Wars were related or the same thing for most of my childhood. I didn't want Star Wars because I'd seen Star Trek on TV and not liked it (I was young).
It's just something people do (or at least I do). I think it's maddness to prevent the use of names starting with "Face" because of this confusion. I thought that iPlayer was apple related like iTunes for a long time. It's confusing yes but I don't feel you should be able to prevent someone using a similar sounding name.
At some point, and this is why the Star Trek / Star Wars example matters, consumers realize that the prefix is generic within the scope of a given market. Telecommunications and faces overlap a lot these days.