(As discussed here)
Despite Jeff being against it, I suspect that people are going to carry on asking for private/direct messaging. The main reason invoked that I have seen is being able to send other people 'private' contact details.
I think that if you satisfy that need, it might remove some of the strength of the demand.
Idea: people could enter their contact details once in their profile, then you'd have a special syntax/button for making them visible to a specific user.
(This is more of a feature-suggestion than a feature-request, but I didn't want to create another tag)