For those who know and love the 'YouTube Honors' that identified popular content on YouTube, there will now be 'YouTube Medals'.
Currently, there are three different medals, each with a gold, silver, and bronze level. The three current medals are All Time Most Popular, Recently Most Popular, and Trending. It seems that more medals may be announced later, but only those three have been made official at this time.
You can read more about YouTube Medals in the YouTube Creator Blog.