This is such a tiny thing, but it's still a little annoying.
Since going over to a new WP7 handset I've had Facebook's "f" logo inside my People tile like so:
It was never there in my old WP7 handset and I've got no Facebook account linked up to my phone/People hub (just Hotmail, Google, Twitter).
It's taking up 1⁄9 of my People tile and masquerading as family/friend and I want rid. Seems it must be a setting, because as I say, it wasn't there in my old handset.