Guys! I tested this with my 3GS and the results were exactly the same!
I have an Incipio Feather case on. It went from 5 bars to one or two bars the minute I picked up the phone in my hand. Couple times it even lost the connection for a few seconds. Weird!
If thats so, then maybe its an issue with the new baseband and/or iOS?
And if thats the case, Apple will be all over it and release 4.0.1