I have made several robots from small hobby projects up to an autonomous driving car (college team). For all of those we used C or C++, with one exception that used Java. For the Java controlled robot I built a web interface that allowed you to control it remotely over wifi (similar to this, without the repeaters).
I have been thinking about using Python or Ruby for the high level logic while using C/C++ down low controlling motors/sensors. Or maybe running a JVM and doing the high level logic in Closure or Scala with JNI over the drivers.
* Since it's easier to write js code than c/c++ code (for me), I would personally prefer it; assuming that the performance degradation is within allowable limits
edit: Apparently, Arduino uses its own programming language: "Arduino hardware is programmed using a Wiring-based language (syntax and libraries), similar to C++ with some slight simplifications and modifications, and a Processing-based integrated development environment." https://en.wikipedia.org/wiki/Arduino