Last I checked, this doesn't permanently delete your account. You can still return with the same email and have all your old contacts (and post history, etc?).
If I remember correctly, this option does delete your account[0], but not right away. If you change your mind and log in within the grace period, it stops it from being deleted.
[0] At least to all appearances. Of course, Facebook could secretly be keeping it, as is discussed elsewhere in this thread.
Yeah, and it's linked. I guess they make it all shady with "let us know" to discourage clicks on it.