This is a new block which creates a slideshow in the header of a site or course page. It uses jquery/cycle to handle the image transitions. Jquery is also used to manipulate the DOM to reposition the block's node into the heading div of the page.
Since this is dependent on using moodle's built in jquery functions, it is not available for versions prior to 2.5.
Update: This block will work with the Clean theme on Moodle version 2.5.2 where MDL-41516 has been fixed.
Via Miloš Bajčetić, Rui Guimarães Lima