RE: '06 Red blinking light - what is it?
Well, after much digging around on the hmaservice.com website, I found the answer to my own question. Read on if you're curious.
The blinking light I mentioned is called the Security Indicator, and it's set to do exactly what I described. According to the service manual, the light is programmed to come on for .3 seconds, then go off for 2 seconds continusously when the key isn't in the ignition. When the system is first armed, the light is programmed to come on for .3 seconds, then go off for .5 seconds. This sequence repeats for 8 seconds, after which the blinking reverts back to the .3 second on/2 seconds off interval. Apparently, the light will also go through a .3 seconds on, 5 seconds off cycle if the alarm is tripped or the panic button is pressed (it's after 11pm as I write this, so I don't think I'll verify that bit of information just yet). The service manual also mentions that the light goes out and stays out as long as the key is in the ignition.
So I guess the light is nothing more than a theft deterrent. I suspected as much, but the irregular interval at times and the fact that the light flashed even when the alarm wasn't armed had me stumped. I guess it's Hyundai's way of making it look like there's an active alarm even when the alarm isn't armed. Pretty clever. The 9-10 quick flashes when the door lock button is pressed is apparently a visual cue to the driver that the system is indeed armed.
The only thing I'm still a little confused about is why the owner's manual has absolutely no reference to the Security Indicator light or what it tells you as the operator.