Maybe instead of using rsync, you can implement your own crossplatform version of rsync. You could also multithread is and/or use the multiprocessing module to provide multiple CPU support so copying can go much faster.
Another good idea is to make a daemon out of it, and have it backup to a certain source at given times every so often. Consider using wxpython for GUI, and docking the daemon on the system tray. It would be pretty sweet.
This would be cool, maybe I can evolve it as I go. But right now this is really my first Python program. If you don't mind helping out I would appreciate it. Like I said at this point I would like to stick with rsync and get my hands around it, then later move to the cross platform idea.
I will do some looking around, I think I have seen some discussions about rsync being used on Windows, and since Mac are realy running shiny Linux/BSD it should work there to.
thanks for the input
coffeebox