Regarding flashing your drive in Windows; be *very* careful. I flashed mine in Windows as I have done to many Windows PC's, and it worked....apparently. Ultimately a few days later I went to reboot my iMac and it wouldn't reboot. My superdrive was dead.
Here is what I do now:
1) buy a cheap external dvd writer/player that does have region free firmware.
2) Boot up into Windows through Parallels or Fusion.
3) Connect your external drive AFTER booting up into Windows.
4) Select virtual machine when you are asked if you want this machine to be available for OS X or virtual machine.
5) Flash the drive.
Now you will be able to use the drive in either OS X or Windows region free. Additionally, if you are ripping DVD's, use this drive in Windows to rip the DVD's using DVD Decrypter after it is mounted as described above.
Hope this helps
Tom
Feel free to pm me if you need help or advice.
I've got an LG super multi writer that I use.
[edit: I downloaded the stock firmware for my 59$ external burner and downloaded a program called MCSE (media code speed edit), loaded the firmware, and applied an rpc-2 reset tool, and then flashed the drive with the modified firmware while in windows. Verfied that the DVD drive still worked, and then went to view a region 2 PAL DVD in OSX. It asked me to change the regiom, and then I switched back and forth between r2 and r1 dvd's. When you reach the limit for the number of region changes, you unplug or power off your external burner, restart/plug in and then the region count is reset. But again, be careful....you can bork your built in burner....always use an external burner to do this]