Programming Language for ROS
According to ROS introduction,
Language independence: the ROS framework is easy to implement in any modern programming language. We have already implemented it in Python, C++, and Lisp, and we have experimental libraries in Java and Lua.
Based on my experience, most of people use C++ and Python.
JSK in University of Tokyo people use Lisp.
In IAI in University of Bremen, Java is one of the main languages.