How do I implement a Facebook like privacy settings for extended User?

[Alex Richards]

I have an extended UserProfile to which I want to add some privacy settings as in Facebook. 

the options for a single field  (say email for now) should be,

public - any one can view his email
friends_of_friends - only friends and friends of friends can view his email
friends - only his friends can view his email
friend_list - only a list of friends (pre defined) can view his email.

The same should be applicable for other fields too (say phone, education, work, likes, activity etc .. ).

Can anyone guide me on the right path? I don't need code but ideas would help.

Thanks.