I've found this hack somewhere on the internet, it works for my R2 player.

1) Turn on the player with no disc in the tray
2) Press the Open/Close button to open the tray
3) Press the info button, the firmware version shows up (mine was 080220.13.B.1080PXKEG)
4) After the version info disappears, close the tray again by pressing the Open/Close button
5) At this point, it will show "no disc" at the top. Press the Info button again, and this will disappear.
6) Now type the code that applies for your region (R2 is 57538). A '2' will briefly show up at the top left corner
7) Now press 9, and 9 will show up in the top left corner
8) Power off the player, and turn it on again. You'll have a multi region player

I've found the following codes at the 1080P7 hack:
R1 - 29334
R2 - 57538
R3 - 56732
R4 - 76884
R5 - 53814
R6 - 24462

Not sure if all are correct, but it worked for R2.

Finally I've been able to hack a Region 4 Samsung DVD 1080P8 using a combination of information from different forums. Here it is:

Turn on the player. Open tray. Make sure there is no disc. Press "INFO". The firmware number will appear. Close tray.
Wait until "no disc" appears. Press "INFO" again. the "no disc" sign will disappear. Press 7-6-8-8-4. the number "4" will appear on the upper left corner. Press 9 and that number will replace the 4. Press "Repeat". Turn off the player. Turn it on and it will now read any region disc. Enjoy watching!

For other region players, please replace 76884 with the one corresponding for your region found in the 1080P7 thread.