From a statement:
"Breitbart News has stood by me when others caved. They have allowed me to carry conservative and libertarian ideas to communities that would otherwise never have heard them. They have been a significant factor in my success. I'm grateful for that freedom and for the friendships I forged there. I would be wrong to allow my poor choice of words to detract from my colleagues' important reporting, so today I am resigning from Breitbart, effective immediately. This decision is mine alone. When your friends have done right by you, you do right by them. For me, now, that means stepping aside so my colleagues at Breitbart can get back to the great work they do."
Why he resigned: for comments on sex between adult men and minors on a podcast that surfaced over the weekend. Yiannopoulos has now lost a CPAC speaking slot, a book deal and his role at Breitbart News.
What's next: he'll give a press conference shortly.