I'm not certain exactly what althekiller had in mind, but I've used the "socket" library in the past to set up socket connections. Every time you run your script (whatever responds to the keypress, that is), it tries to contact the server, and if no server is available it runs the script that launches the server.
The server then sits and listens on a certain port for recognized commands. When it receives a command (probably an info request), it establishes a connection and returns whatever information you want from it.
On the keypress, then, you would just launch a client that connects to the server, gets whatever information it's providing, and then displays it.
You can probably find much better generic examples of socket connections searching for "Python socket," but you can find a specific implementation of it in my very old (and, I'm sure, completely obsolete)
XMonitor script.
