This icon denotes when a listing is new within the last 24 hours.  If you do a lot of searches you will see this item a great deal.  This lets you know if you are looking at the same old pages when something new is on the horizon that you may not have spotted before.    to see all the icons and all their defintions & what they stand for - that eBay uses please go to http://pages.ebay.com/help/find/icons.html