Randi Zuckerberg, co-founder of Facebook, sister to Mark, and director of marketing for the social network, has handed in her letter of resignation. She plans to launch RtoZ Media, a social media firm.

“My goal is to launch my own innovative programming and work with media companies to develop their programming in new, and more social ways. In attacking this challenge, Facebook will clearly be a central element in all of my projects,” she said in her resignation letter.

It was only last week that she was at the Hearst Tower talking about Facebook and online privacy with Erin Andrews, Chelsea Clinton, and Marie Claire! She’s in the photo above at the event, second from the left.

[via AllThingsD]