My reasoning on thinking its the antenna is because if the design is actually unibody aluminum, it would have to have access outside of the body to get a good signal, and since it is exposed on all the official cases (not the knock off chinese rip offs) its a good indicator, but again, it could just be a rubber nub that covers a screw that holds the phone's metal piece together around the kickstand, so its hard to say, but that wouldn't explain why it would be exposed on cutouts of cases when a case would keep the phone enclosed...
just speculation on that, i never got a real answer on it
I too would like to know this

I'm hoping we get a desk dock this time too unlike the Incredible getting its canceled because it wouldn't go into landscape for Sense.
@
PSYCHotIcJonny
When you get a working unit in, can you please check to see if it goes into Landscape when the phone is turned on its side, all the CES and Wirefly videos show it doesn't ... but i'm hoping its just the orientation widget thats keeping it locked into portrait mode
if not, i guess the XDA guys have there work cut out for them when the phone launches to get a custom ROM out to enable this since it has root (hopefully will work on the production model)
considering the Droid X dock should fit the ThunderBolt, i wonder if it would work... hmmm
i still have mine
and i'll shutup now lol