I have written a very simple script for my raspberry pi that loads an uncompressed WAV and plays it - however when I run the script as root (to be able to use GPIO and ServoBlaster), there is no sound output.  
I have set the default audio device to a USB sound card, and this works - I have tested this using aplay fx.wav.
Running the pygame script without sudo, the sound plays fine.  
What is going on here?
The issue was the sudo command changing the directory in which the script was being run - so running python with sudo -s or simply using an absolute path for the sound fixed it.
When running a pygame script as root, no sound is output?