Some people are unable to be contacted

Over the last couple of weeks, I've seen a couple of people try to contact another person on Launchpad, only to be stumped by the lack of public contact details.

In one case, a project maintainer wanted to talk with someone who submitted a branch to his project. The branch owner has not made their email address public, nor have they provided Jabber details. There's no obvious recourse for the project maintainer.

In another case, one translator wanted to contact another to discuss the quality of their translations and provide suggestions for improvement.

    <jml> yeager: out of curiosity, why do you want to contact them?
    <yeager> jml: he's translations are terrible bad and I need to give him some directions

Perhaps there should be a way of sending someone a message through Launchpad.

For the branch case, perhaps it should be more obvious that editing the branch whiteboard will send a note to the owner. Perhaps there should be a discussion associated with the branch.