As announced by incoming OSF head Chris Stone, US programs have a new head.  It is Kenneth H. Zimmerman. The OSF profile notes his legal aid roots:

Zimmerman began his career as a legal services lawyer in Oakland, California, where he successfully challenged discriminatory actions by FEMA in the aftermath of the 1989 Loma Prieta earthquake.

Here is a more complete bio.

As Chris Stone sums it up:

Ken’s experience makes him superbly qualified to lead our U.S. work. Collaboration among public, private, and nonprofit sectors is crucial to turning smart ideas and hard work into real world results. I look forward to his help as a partner in carrying on the efforts of the Open Society Foundations to promote democratic governance, rule of law, the rights of minorities, and civil and political liberties.