The second scripting language implemented in radare was 'python'. Lot of people ping me for adding support for python scripting. The python interface for C is not as nice as the LUA one, and it is obviously not as optimal as LUA, but it gives a very handy syntax and provides a full-featured list of libraries and modules to extend your script.
Actually in python-radare is possible to write a GTK frontend (for example) by just using 'H python "your-script"' and using from the the core radare.py API.
The basics of the scripting for any language is the same. The entrypoint between the language and the core is a 'str=r.cmd(str)' function which accepts a string representing a radare command and returns the output of this command as a string.
The file 'radare.py' implements the API for accessing the raw 'r' module which is only loaded from inside the core. (So you cannot use radare-python scripts outside radare (obviously)).
The file 'radapy.py' implements a pure-python radare-remote server and enables a simple interface for extending the basic IO operations thru the network in python. Read 'networking' section for more information.