Ok, I fugured it out.
Here's the solution:
Change the following code in the itemListLeading div foreach loop in the category.php around line 152.
<?php
// Load category_item.php by default
$this->item=$item;
echo $this->loadTemplate('item');?>
With this code:
<?php
// Load category_item.php by default
$this->item=$item;
?>
<?php if($item->featured == 1): ?>
<?php $x++; ?>
<?php if($key == 0): ?>
<div class="itemListHead">
<h2><?php echo JText::_('K2_ITEM_LIST_HEAD_FEATURED'); ?></h2>
</div>
<?php endif; ?>
<?php elseif($item->featured == 0): ?>
<?php if($key == $x): ?>
<div class="itemListHead">
<h2><?php echo JText::_('K2_ITEM_LIST_HEAD'); ?></h2>
</div>
<?php endif; ?>
<?php endif; ?>
<?php echo $this->loadTemplate('item'); ?>
Of course, you will have to add K2_ITEM_LIST_HEAD_FEATURED & K2_ITEM_LIST_HEAD to your language overrrides.
It even works with pagination too !
So there it is, hope someone finds this usefull.
Peace.