AFAIK @steemed and @kushed and some other people have been trading accounts or helping/escrowing. And @blocktrades has sold some accounts with much Steem Power. Also in the bitcointalk thread there have been some discussions. There was a account trading channel in the old Slack, but I didn't find one in https://steemit.chat . Oh, @steemitmarket has been selling accounts but I don't know how many did he sold (link is here).