Both in Twitter and Friendfeed (and probably an awful lot of other applications) there is a design flaw regarding users protecting their updates. As you might know you can only read updates of users that protect their updates after they gave you permission for it.
However if you do not protect you updates (and give it a thought, why would you want to protect your updates, or are you talking about homeland security? Then you should not use these tools at all), the users that protect their updates are free to add you to follow you. However if you want to follow them back, you have to do a request…
Is it technical?
I understand the technical decision why you have to do a request: the user protected his updates and to see them, he has to approve you. However it does not feel right and it feels morally wrong to me, also there is an inequality created in the relationship of the users . Especially since if you want to get to know that person, or if you want to know what subjects this person is talking/ tweeting about, you first have to request and then you can decide whether if you want to follow back or would rather like to block this person since his content is objectionable.
The correct design for these kind of systems should be that if an user that protects his updates starts following somebody, he automatically grants that person access to his updates. With this method you create transparency between follower and followed one, and also you create an equal starting position for both parties. They both can see what the other one is talking about and decide whether the relation that is started by the one is worth to be mutual or should be ended as soon as possible.
Stalkers and voyeurs
Why would you want to keep your updates protected for a person if you follow that person? It would be like wearing a ski mask: the person wearing the mask can see you, and even follow you around, while you have no clue who that person is, and why you are so interesting to him. You won’t even have the opportunity to ask him!
So: if you would like to follow someone, take of your mask, or let the network do it for you.