It’s about time. Not just because Facebook went public with an all-male board, but also because Sandberg is widely-viewed to be the business yin to Mark Zuckerberg’s vision yang.

“Sheryl has been my partner in running Facebook and has been central to our growth and success over the years,” Zuckerberg said in a prepared statement. “Her understanding of our mission and long-term opportunity, and her experience both at Facebook and on public company boards makes her a natural fit for our board.”

This will represent an expansion of the Facebook board, as no current directors are expected to step down. Existing board members are Zuckerberg, Marc Andreessen (Andreessen Horowitz), Erskine Bowles (UNC), Donald Graham (Washington Post Co.), Reed Hastings (Netflix) and Peter Thiel (Founders Fund/Clarium Capital).

Related link: Slaughter vs. Sandberg: Can women have it all?