At Admin Panel -> Settings -> Switches, the "new/updated icons" switch enables icons which indicate that a topic is new, that a topic has been updated recently, or that a forum has new topics in it. These icons appear next to the forum/topic name in the topics. The icons are actually just yellow text that says new or updated, not graphics anymore. The template variables are {LINKNEW}, {LINKISUPDATED} and {CATHASNEW} -- used in the topic bit and forum bit templates. If you want to restyle them, they all use the CSS classes icons and updatedcontent.