I proposed it in a comment a month ago after the top 1000 writers were given $500 each. At the end of May, the top 1000 writers were given $500, then writers 1001-1500 were given $100 and writers 1501-2000 were given $50. I'm sure you'll find plenty of stories covering it - as always, Medium is keeping its cards close to its chest and so there is no announcement. :o)