Thanks for the response, sounds like you're the person to talk to.
I'm not trying to do anything fancy, just turn on the LED at pin 13 of my Diecimila. This is the code I was using after changing the serial rate in pyduino.py like you suggested:
import pyduino
a = pyduino.Arduino("com5")
a.digital[13].set_active(1)
a.digital[13].set_mode(pyduino.DIGITAL_OUTPUT)
a.digital[13].write(1)
The firmata sketch uploads fine, the rx/tx lights blink while it runs, and I don't get any errors in Python, but nothing else happens. I know it's not a communication issue; I have sent and received serial data from my Arduino in several other instances. PySerial and the FTDI drivers are installed (I'm on Python 2.5). Any idea as to what's going wrong? Thanks again for your help.