From wordpress 3.1 onwards l10n.js is added to the head section of the page automatically.
Purpose of l10n.js in wp head
L10n.js (ya its not i10n) is added in the wordpress head automatically to convert the html entetities into the read characters they represent. This have various practical and security applications.
How to remove l10n.js from wp head
Removing this file from the wordpress head is really very simple.
Simply paste this line of code in the functions.php file of your current wordpress theme:
wp_deregister_script( 'l10n' );
This will remove the l10n.js file from being added to wp_head of your theme automatically.