I just confirmed with Larry that we're going to build a way for users to send private messages to one another, but the recipient will be able to flag the message as spam/abuse.
We don't know yet exactly what it will look like, but it's on the "to-do" list.
I think that the only people that should be allowed to private message you are Administrators, Moderators and people that you've added to your friends list. Or have followed.
GoM, as we've already stated (several times), you will have control, via the Privacy Settings, to allow or block certain users from sending you private messages. If you want to allow your Friends but not your Followers, you can do so. If you want Friends and Followers, but not total strangers, you can do so. If you want EVERYBODY to be able to send you messages, you can do that too. Or you can turn them all off, and only mods/admins can send you private messages.
I think it would work well because many people only want to send a private message to a popular person but it will be seen as they are sooooooo popular.
