Thank you for the link to bitty.py, where I read...
The python program known as bitty.py is a serial port proxy. It runs on an Arduino-connected PC and makes the Arduino available over the network for connection via telnet, nc, or your favorite telnet client.
The access-from-internet serial proxy route is an interesting idea. I wasn't clear why the spec speaks of an Arduino-connected PC. I thought that that one of the points of serial proxys was that at that level, WHAT was connected via the serial link was irrelevant?
As for software to run in the Arduino to react to things and send out things, in and out over the serial link... I'm okay on that side of things, and hope they can go in other threads, if others wish to discuss them.
So... one "vote" for Python as the working environment in the PC?