User blog comment:Jimeee/Skyrim 1.9 beta update adds Legendary difficulty and raises level cap (Updated Apr 8th)/@comment-4096563-20130304191609/@comment-6296105-20130304200250

It looks like, to me, that it allows you to gain un-modded extra perks in Skyrim. I have a mod for this, but it's nice for those poor console users who can't access the Steam Workshop.