The way I understand it, removing the plist files, which are, like all plist files, just "preferences list files," enabled the system to recreate good plist files that worked with 10.8.2 and the HDMI hardware/firmware in the rMBPro.
Just about everything in the Mac requires its own plist file, and often, when something isn't working, like wi-fi or sound or screensaver or whatever, removing the associated corrupted plist file(s), if you can find them, lets the Mac then recreate good plist files. All that happens when you remove a plist file is that you lose some settings.
After removing the windowserver plist files in my system from the original 10.8.2 update, new windowserver plist files were created that worked fine. After installing the next software update, as I mentioned in an earlier post, I had to go through the plist removal process again to make HDMI work. I did not have to do that with the second software update, for whatever reason.
This is what I have in my system right now:
System Version: OS X 10.8.2 (12C3006) This includes all supplemental software updates.
I have com.apple.windowserverxxxx.plist files in all the directories, and my HDMI output works perfectly now.
My suggestion to you would be to reinstall 10.8.2, then either let Software Update install the two supplemental software or else install the updates manually. Then, if HDMI still doesn't work, try removing the windowserver plist files that have been created, reboot with the HDMI cable plugged in both to the Mac and to your TV or monitor or whatever, doing a PRAM reset while doing the reboot.
If this doesn't work, then you'll have to call AppleCare for help.
