WordPress MU

I have searched high and low, have found <?php _e('Contact Info') ?> but cannot simply locate a method to changing say "AIM" to Skype for the purposes of displaying SKYPE address instead of something that is really kind of outdated e.g. AIM

I see where foreach (_wp_get_user_contactmethods() as $name => $desc) but where are the relationships? Which file can I simply go to and define $desc as SKYPE?

You don't want to hack the core that way. If you'll notice, in wp-includes\registration.php, the code sets up the contact methods and includes a filter

function _wp_get_user_contactmethods() {
	$user_contactmethods = array(
		'aim' => __('AIM'),
		'yim' => __('Yahoo IM'),
		'jabber' => __('Jabber / Google Talk')
	);
	return apply_filters('user_contactmethods',$user_contactmethods);
}

So, you would write a plugin that returns what you want to return, instead of the standard.

<?php
/*
Plugin Name: cets_modify_contact_methods

Description: replaces AIM contact field with SKYPE contact field
Author: Deanna Schneider
Version: 1.0
Author URI: http://deannaschneider.wordpress.com

Released under the GNU General Public License (GPL2)
http://www.gnu.org/licenses/gpl.txt

This is a WordPressMU plugin (http://wordpress.org)
*/

function cets_modify_contact_methods() {
	$user_contactmethods = array(
		'skype' => __('SKYPE'),
		'yim' => __('Yahoo IM'),
		'jabber' => __('Jabber / Google Talk')
	);
	return $user_contactmethods;
}

add_filter('user_contactmethods', 'cets_modify_contact_methods');

?>

Save that code to a file and upload it to mu-plugins and voila - aim is skype.