I’m a victim of what Facebook says a ‘mistake’ or ‘someone has mistakenly register my email address’ for an FB account. I doubt it’s a mistake. Not sure how their system work but knowing I’m receiving plenty of FB invitation from contacts, I think FB’s system is set to auto-create the account… hoping for another user in their service.
More info with screenshots in http://www.calendarofupdates.com/updates/index.php?app=blog&module=display§ion=blog&blogid=2&showentry=308
A discussion in CoU on how to delete your FB account, if you don’t want it anymore (that is if you have an FB account… created by you).