A great read from Kashmir Hill at Gizmodo about how Facebook doesn’t keep profiles for non-users, but it does use their contact information to connect people:
What if you don’t like Facebook having this data about you? All you need to do is find every person who’s ever gotten your contact information and uploaded it to Facebook, and then ask them one by one to go to Facebook’s contact management page and delete it.
Bad news folks. It doesn't matter if you've never even created an account on Facebook, it still knows about you. And there's next to nothing you can do about it.
At the very least, if you must have a Facebook account don't ever grant it access to your address book and contacts, and use a unique email address (rather than your regular one) when you create an account.