I finally found why my connection does not drop when i apply the death grip on the iPhone 4. Apparently the antennagate only applies to 3G connections and like any phone the network will fall back to a GSM/EDGE network when the 3G connection fails or is low. This is an inherent Telco Grade system feature. If you are facing drop calls, it's really because you are in a dead zone. 

As you can see in the video, on 3G the death grip brings the iPhone 4 from 3 bars to 1 bar, but surprisingly, I have never seen the iPhone go beyond 1 bar, switch to GSM/EDGE or No Service notification. What i found out yesterday is that when I turned off 3G going to the fall back GSM/EDGE network, i cannot apply the death grip on it. It shows full bars (Since it was like 2am in the morning i waited till this morning to do this post)

That is when I realised that like most any other phone, it is intelligent enough to keep you connected through it's cell network to keep the connection going. This is probably because it is Singapore where the cell coverage here is nationwide. You can see in the previous experiment, it does not really disable my network connections because of this - http://mikefoong.com/theitchannel-iphone-4-death-grip-experiment

Here is the video:

Ok I confess, I have been trying to kill my iPhone 4 with my Sith death grip that is worthy of Darth Vader.

I did 2 experiments just make sure that it is repeatable. I held it so tight that could literally choke some small animal to death. You can see that the iPhone signal did drop but not so much that it completely render the phone useless.

Here are the videos

Part 1 of the Experiment

Part 2 of the Experiment