Here is what I got for MSN and there is zero functionality, all it will do is display the image and have the username in the alt= statement.
$postrow[$i]['Extra5'] = ($userextra5) ? "<img src=\"{$config['images']}/msn-icon.gif\" alt=\"{$userextra5}\" title=\"{$userextra5}\" border=\"0\" /></a>" : "";
The way the mod over at ubbdev has it is they just add an alt= statement saying "so and so uses MSN []
[email protected][/] and that's it

IMO the best thing that can be done with this is to have it link to the users profile, do you have a quick and easy line of code for that?