It quite simple, no big hacks. In fact, Joomla already had it build in, it is just not shown in the admin menu (don't ask us why.
simple change the file: administrator\components\com_content\config.xml.
and add somewhere between the other items:
label="Sef Advanced Mode"
description="Remove ItemID from Content URL?">
Now go back to your article options, and you have a new option :) SEF Advanced Modus, just put it on and your done :)