On Facebook I got greeted today by a window offering me to import all my friends from my mail accounts address book to Facebook. They promise not to save any passwords. They copy the whole address book onto their servers, though, and create statistics (also about not registered people). If one of those people then registeres with Facebook, you will get a friendship request automatically. They also save phone numbers. Those are data, which I don’t want Facebook to have.
For those who used this function once und now want to remove all the stored data (and that is, why I am writing this article), use this link: http://www.facebook.com/contact_importer/remove_uploads.php
[UPDATE:]
Till now I thought that you can Facebook, if you follow their rules – like free interpretation of their words – seriously. At least I did not think of something like this (linked homepage is in German).