I too am getting a replacement for my handset. I was one of the few idiots that actually hard-bricked his Vibrant. I ran the Samsung Kies update for 2.2 and kaboom, it simply wouldn't turn on.
Whatever the case may be, I have an FFC and need to fill the hole as well, for obvious reasons. My first attempt is gonna be duct tape, as it's the easiest to do and revert from in case of any physical mishap. I fear that a black marker will leave significant streaking, as will any light pen or nail polish. Might have to go with paint or possibly raw ink. I guess I'll post my results/conclusion. Thanks for all of those who contributed to this thread.