There's also http://www.tinypy.org/ http://www.tinypy.org/ which should be better known. It's not "for microcontrollers", but it is quite small - fits within 64

There's also http://www.tinypy.org/ http://www.tinypy.org/ which should be better known. It's not "for microcontrollers", but it is quite small - fits within 64k, mostly complete py2 language implementation, has a luaesque API and GC (that is, not reference counting).