Samantha Power (left) and Jennifer Pahlka (right) speak at TED2008 and TED2012, respectively.

Today, Barack Obama will be naming a new U.S. ambassador to the United Nations – and sources say that it will be Samantha Power, outspoken anti-genocide official and TED2008 speaker. Power is expected to replace Susan Rice, who sources say will be named national security advisor.

Samantha Power: A complicated hero in the war on dictatorship Power is a fascinating choice for this very important role. She’s been a longtime aide to Obama; when the president established an Atrocities Prevention Board in 2012, he named Power as its chair. Power also served as the National Security Staff’s Senior Director for Multilateral Affairs and Human Rights from the beginning of Obama’s term through February 2013, when she left to spend time with her husband and two small children. A statement at the time said she was “likely to return to the administration.”

Power’s TED Talk gives us the feeling that she will deeply embrace her role as UN ambassador. At TED2008, she spoke with intense passion about the rise of the anti-genocide movement in the United States in recent years. She also tells the story of Sergio Vieira de Mello of Brazil, a UN diplomat for 34 years who was killed in a suicide bombing in Iraq in 2003. Listen as she tells the story of how he tiptoed across difficult moral lines to save lives in the world’s most broken places, and the lessons she learned from his career.

Meanwhile, Jennifer Pahlka — founder and executive director of Code for America and a TED2012 speaker – announced big news of her own. She is joining the staff of the Office of Science and Technology Policy at the White House, serving as the Deputy Chief Technology Officer for Government Innovation for the a year. Jennifer Pahlka: Coding a better government In a blog post, she writes that she’s taking the role for two reasons –  to help the government embrace technological innovations, and to gain a deeper understanding of what it’s like to work inside government for when she returns to Code for America.

We’ll be closely watching what Pahlka does in this new role. In her TED Talk, she asks people who’ve given up on government to give their withdrawal a closer look. “Technology is making it possible to fundamentally reframe the function of government in a way that can actually scale by strengthening civil society,” Pahlka says. “And there’s a generation out there that’s grown up on the Internet, and they know that it’s not that hard to do things together – you just have to architect the systems the right way.”