I just got a request on MySpace, asking me to add them as a friend.
So I logged in (first time I've done so in... a year, perhaps?), and had a look at their profile to try to figure out who they are, since their displayed name wasn't very informative.
And got told, "This profile is private; the user has to add you as a friend before you can read their profile".
I would have thought it would be a good idea to have profiles visible to anyone you want to add as a friend, at least for a limited time. (From the little bit of poking around Facebook I've done so far, this seems to be the case there -- at least, poking someone makes your profile visible to them for a certain period, and I think that asking for friendship did so, too.)