mystery plug near E Brake

I'm new here, im normally on themustangsource but there down and i need this help so thought i'ld give these fourms a try. heres my problem/question:

I was working on hardwiring my XM Radio and noticed a plug thats not plugged into anything near the ebrake. Its actully below where the cup holders usallly are. the wires under there are

1. gorup of wires going to e-brake (assuming the wires for the dash e brake warning light)
2. 2 wires for the outlet in the center compartment.
3.mystery plug

i took some pictures of it and posted them here Photobucket

here is the one with the plug circled

I was hoping some one knows what this plug is for and how many volts run through it and if its switched like the radio. if it is i can use this for my xm radio instead of taping into the wiring of the radio.

Yes i do have a man. that woudl make since about what the plug does. i think when i get back to my house friday i'll use my multimeter to find out how much voltage is running through there although i serously doubt that its enough to run my xm.