To those having an issue with iMessage, the issue is your Mac's serial that us checked by iMessage during registration, which is located in your nvram. The fix is actually pretty simple.
1. Open Terminal
2. Copy and paste this command
Code:
sudo nvram 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:MLB=(6 randomdigits)
3. After the "=" in the command copy and paste your Mac's serial from System Profiler and add 6 random digits to the end of it then run the command.
@HackerWayne and @MLForAll it would be nice if you guys added that little command to MavericksPostFactor pretty please