Hey, I have written a little script to pause the banshee when the screensaver turns on, and unpause banshee if it was paused when the screensaver is turned off.

The python script is here:
https://gist.github.com/1387945

If you want to use this:
  1. Go to the link
  2. Click the raw link
  3. Save the script somewhere
  4. Add "python /script/directory/screensaver.py" to one of the programs to start with the session


Have fun tinkering with the script