Not that I'm aware of, which is rather unfortunate. One way to do this might be to take an existing open source SPICE implementation such as NGSPICE (http://ngspice.sourceforge.net/) and build a GUI around it that provides the real-time visualization of the signals.

In the meantime, if you're looking for a free, easy-to-use circuit simulation tool, I've used LTSpice (http://www.linear.com/designtools/software/) in the past for my EE classes. The Windows version runs pretty well under Wine and the UI isn't too shoddy. It's pretty far away from Bret Victor's vision though, as you need to rerun the simulation again in order to see a new plot of the node voltages and currents.