The other interesting and recent "Python in the browser" project is RapydScript - https://github.com/atsepkov/RapydScript

Unlike PythonJS, it does not have the goal of being 100% Python compatible, but instead takes the CoffeeScript approach. So, like Coffeescript, you get (mostly) clean Javascript output, no huge library dependency, runs nearly as fast as Javascript, etc.

Check out the "ants" demo - http://salvatore.pythonanywhere.com/RapydBox/default/editor

I've been playing around with both PythonJS and Rapydscript, and I like both. Different goals. PythonJS can output to Lua, too - so there's the whole Python in LuaJIT angle which could be very interesting as it matures.